Bump pmd.version from 6.39.0 to 6.40.0

Bumps `pmd.version` from 6.39.0 to 6.40.0.

Updates `pmd-core` from 6.39.0 to 6.40.0
- [Release notes](https://github.com/pmd/pmd/releases)
- [Changelog](https://github.com/pmd/pmd/blob/master/docs/render_release_notes.rb)
- [Commits](pmd/pmd@pmd_releases/6.39.0...pmd_releases/6.40.0)

Updates `pmd-java` from 6.39.0 to 6.40.0
- [Release notes](https://github.com/pmd/pmd/releases)
- [Changelog](https://github.com/pmd/pmd/blob/master/docs/render_release_notes.rb)
- [Commits](pmd/pmd@pmd_releases/6.39.0...pmd_releases/6.40.0)

---
updated-dependencies:
- dependency-name: net.sourceforge.pmd:pmd-core
  dependency-type: direct:production
  update-type: version-update:semver-minor
- dependency-name: net.sourceforge.pmd:pmd-java
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

pom.xml

@@ -81,7 +81,7 @@
     <maven-surefire-plugin.version>3.0.0-M4</maven-surefire-plugin.version>
     <maven-jar-plugin.version>3.2.0</maven-jar-plugin.version>
     <maven-pmd-plugin.version>3.15.0</maven-pmd-plugin.version>
-    <pmd.version>6.39.0</pmd.version>
+    <pmd.version>6.40.0</pmd.version>
     <maven-checkstyle-plugin.version>3.1.2</maven-checkstyle-plugin.version>
     <checkstyle.version>9.0.1</checkstyle.version>
     <spotbugs-maven-plugin.version>4.4.2.2</spotbugs-maven-plugin.version>