MINOR: Bump version to 18.3.0 (#741)

diff --git a/adapter/avro/pom.xml b/adapter/avro/pom.xml
index 827d19f..cf9d353 100644
--- a/adapter/avro/pom.xml
+++ b/adapter/avro/pom.xml
@@ -23,7 +23,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
diff --git a/adapter/jdbc/pom.xml b/adapter/jdbc/pom.xml
index 2f621d7..f92863f 100644
--- a/adapter/jdbc/pom.xml
+++ b/adapter/jdbc/pom.xml
@@ -23,7 +23,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
diff --git a/adapter/orc/pom.xml b/adapter/orc/pom.xml
index e3ae7d5..e60a7ce 100644
--- a/adapter/orc/pom.xml
+++ b/adapter/orc/pom.xml
@@ -23,7 +23,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
     <relativePath>../../pom.xml</relativePath>
   </parent>
 
diff --git a/algorithm/pom.xml b/algorithm/pom.xml
index 898c260..e934eb7 100644
--- a/algorithm/pom.xml
+++ b/algorithm/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
   <artifactId>arrow-algorithm</artifactId>
   <name>Arrow Algorithms</name>
diff --git a/bom/pom.xml b/bom/pom.xml
index 61b452b..80f03d1 100644
--- a/bom/pom.xml
+++ b/bom/pom.xml
@@ -29,7 +29,7 @@
 
   <groupId>org.apache.arrow</groupId>
   <artifactId>arrow-bom</artifactId>
-  <version>19.0.0-SNAPSHOT</version>
+  <version>18.3.0</version>
   <packaging>pom</packaging>
 
   <name>Arrow Bill of Materials</name>
@@ -68,7 +68,7 @@
   <scm child.scm.connection.inherit.append.path="false" child.scm.developerConnection.inherit.append.path="false" child.scm.url.inherit.append.path="false">
     <connection>scm:git:https://github.com/apache/arrow-java.git</connection>
     <developerConnection>scm:git:https://github.com/apache/arrow-java.git</developerConnection>
-    <tag>main</tag>
+    <tag>v18.3.0</tag>
     <url>https://github.com/apache/arrow-java/tree/${project.scm.tag}</url>
   </scm>
 
diff --git a/c/pom.xml b/c/pom.xml
index c90b6dc..290cb56 100644
--- a/c/pom.xml
+++ b/c/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>arrow-c-data</artifactId>
diff --git a/compression/pom.xml b/compression/pom.xml
index 6f60eb7..3443f11 100644
--- a/compression/pom.xml
+++ b/compression/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
   <artifactId>arrow-compression</artifactId>
   <name>Arrow Compression</name>
diff --git a/dataset/pom.xml b/dataset/pom.xml
index 6e56d55..efbe310 100644
--- a/dataset/pom.xml
+++ b/dataset/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>arrow-dataset</artifactId>
diff --git a/flight/flight-core/pom.xml b/flight/flight-core/pom.xml
index a32293a..757de85 100644
--- a/flight/flight-core/pom.xml
+++ b/flight/flight-core/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-flight</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>flight-core</artifactId>
diff --git a/flight/flight-integration-tests/pom.xml b/flight/flight-integration-tests/pom.xml
index 78a2d08..e7fb999 100644
--- a/flight/flight-integration-tests/pom.xml
+++ b/flight/flight-integration-tests/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-flight</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>flight-integration-tests</artifactId>
diff --git a/flight/flight-sql-jdbc-core/pom.xml b/flight/flight-sql-jdbc-core/pom.xml
index a2e2b28..a95fbac 100644
--- a/flight/flight-sql-jdbc-core/pom.xml
+++ b/flight/flight-sql-jdbc-core/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-flight</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>flight-sql-jdbc-core</artifactId>
diff --git a/flight/flight-sql-jdbc-driver/pom.xml b/flight/flight-sql-jdbc-driver/pom.xml
index 559c425..3776e97 100644
--- a/flight/flight-sql-jdbc-driver/pom.xml
+++ b/flight/flight-sql-jdbc-driver/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-flight</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>flight-sql-jdbc-driver</artifactId>
diff --git a/flight/flight-sql/pom.xml b/flight/flight-sql/pom.xml
index 5f06a5e..66ade30 100644
--- a/flight/flight-sql/pom.xml
+++ b/flight/flight-sql/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-flight</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>flight-sql</artifactId>
diff --git a/flight/pom.xml b/flight/pom.xml
index 2fc3e89..7b31e8c 100644
--- a/flight/pom.xml
+++ b/flight/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
   <artifactId>arrow-flight</artifactId>
 
diff --git a/format/pom.xml b/format/pom.xml
index d3578b6..9b4eebf 100644
--- a/format/pom.xml
+++ b/format/pom.xml
@@ -23,7 +23,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>arrow-format</artifactId>
diff --git a/gandiva/pom.xml b/gandiva/pom.xml
index 5367bfd..167bf39 100644
--- a/gandiva/pom.xml
+++ b/gandiva/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <groupId>org.apache.arrow.gandiva</groupId>
diff --git a/memory/memory-core/pom.xml b/memory/memory-core/pom.xml
index 72ee69d..840d346 100644
--- a/memory/memory-core/pom.xml
+++ b/memory/memory-core/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-memory</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>arrow-memory-core</artifactId>
diff --git a/memory/memory-netty-buffer-patch/pom.xml b/memory/memory-netty-buffer-patch/pom.xml
index 07dc7d2..e9a63b2 100644
--- a/memory/memory-netty-buffer-patch/pom.xml
+++ b/memory/memory-netty-buffer-patch/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-memory</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>arrow-memory-netty-buffer-patch</artifactId>
diff --git a/memory/memory-netty/pom.xml b/memory/memory-netty/pom.xml
index 6d660da..42f35ef 100644
--- a/memory/memory-netty/pom.xml
+++ b/memory/memory-netty/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-memory</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>arrow-memory-netty</artifactId>
diff --git a/memory/memory-unsafe/pom.xml b/memory/memory-unsafe/pom.xml
index 92dc0c9..0af306c 100644
--- a/memory/memory-unsafe/pom.xml
+++ b/memory/memory-unsafe/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-memory</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
 
   <artifactId>arrow-memory-unsafe</artifactId>
diff --git a/memory/pom.xml b/memory/pom.xml
index bc34c26..09a5bc2 100644
--- a/memory/pom.xml
+++ b/memory/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
   <artifactId>arrow-memory</artifactId>
   <packaging>pom</packaging>
diff --git a/performance/pom.xml b/performance/pom.xml
index 3f18188..02bdf46 100644
--- a/performance/pom.xml
+++ b/performance/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
   <artifactId>arrow-performance</artifactId>
   <packaging>jar</packaging>
diff --git a/pom.xml b/pom.xml
index 8360e1b..de24b12 100644
--- a/pom.xml
+++ b/pom.xml
@@ -28,7 +28,7 @@
 
   <groupId>org.apache.arrow</groupId>
   <artifactId>arrow-java-root</artifactId>
-  <version>19.0.0-SNAPSHOT</version>
+  <version>18.3.0</version>
   <packaging>pom</packaging>
 
   <name>Apache Arrow Java Root POM</name>
@@ -81,7 +81,7 @@
   <scm child.scm.connection.inherit.append.path="false" child.scm.developerConnection.inherit.append.path="false" child.scm.url.inherit.append.path="false">
     <connection>scm:git:https://github.com/apache/arrow-java.git</connection>
     <developerConnection>scm:git:https://github.com/apache/arrow-java.git</developerConnection>
-    <tag>main</tag>
+    <tag>v18.3.0</tag>
     <url>https://github.com/apache/arrow-java/tree/${project.scm.tag}</url>
   </scm>
 
diff --git a/tools/pom.xml b/tools/pom.xml
index cb9a161..d60281d 100644
--- a/tools/pom.xml
+++ b/tools/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
   <artifactId>arrow-tools</artifactId>
   <name>Arrow Tools</name>
diff --git a/vector/pom.xml b/vector/pom.xml
index 52ad510..450e4ff 100644
--- a/vector/pom.xml
+++ b/vector/pom.xml
@@ -22,7 +22,7 @@
   <parent>
     <groupId>org.apache.arrow</groupId>
     <artifactId>arrow-java-root</artifactId>
-    <version>19.0.0-SNAPSHOT</version>
+    <version>18.3.0</version>
   </parent>
   <artifactId>arrow-vector</artifactId>
   <name>Arrow Vectors</name>