Bump maven-pmd-plugin from 3.20.0 to 3.21.0 (#341)

Bumps [maven-pmd-plugin](https://github.com/apache/maven-pmd-plugin) from 3.20.0 to 3.21.0.
- [Release notes](https://github.com/apache/maven-pmd-plugin/releases)
- [Commits](apache/maven-pmd-plugin@maven-pmd-plugin-3.20.0...maven-pmd-plugin-3.21.0)

---
updated-dependencies:
- dependency-name: org.apache.maven.plugins:maven-pmd-plugin
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

pom.xml

@@ -693,7 +693,7 @@
           <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-pmd-plugin</artifactId>
-            <version>3.20.0</version>
+            <version>3.21.0</version>
             <configuration>
               <targetJdk>${java.version}</targetJdk>
               <rulesets>