Revert "maven-pmd-plugin 3.11.0 -> 3.12.0."

This reverts commit 1fcd2b82c791d001168465c779dbaf0a955f8beb.
diff --git a/pom.xml b/pom.xml
index 04e3b2f..a9d7845 100644
--- a/pom.xml
+++ b/pom.xml
@@ -487,7 +487,7 @@
       </plugin>

       <plugin>

         <artifactId>maven-pmd-plugin</artifactId>

-        <version>3.12.0</version>

+        <version>3.11.0</version>

         <configuration>

           <targetJdk>${maven.compiler.target}</targetJdk>

         </configuration>