upgrade parent version

git-svn-id: https://svn.apache.org/repos/asf/maven/shared/trunk@1372600 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/pom.xml b/pom.xml
index 2899918..debb268 100644
--- a/pom.xml
+++ b/pom.xml
@@ -25,7 +25,7 @@
   <parent>
     <groupId>org.apache.maven.shared</groupId>
     <artifactId>maven-shared-components</artifactId>
-    <version>16</version>
+    <version>18</version>
     <relativePath>../maven-shared-components/pom.xml</relativePath>
   </parent>