Set next development version to 3.21.0-SNAPSHOT
diff --git a/pom.xml b/pom.xml
index 7b66ff6..4b9ab62 100644
--- a/pom.xml
+++ b/pom.xml
@@ -30,7 +30,7 @@
   </parent>
 
   <artifactId>maven-pmd-plugin</artifactId>
-  <version>3.20.1-SNAPSHOT</version>
+  <version>3.21.0-SNAPSHOT</version>
   <packaging>maven-plugin</packaging>
 
   <name>Apache Maven PMD Plugin</name>