Upgrade PMD to 7.8.0

[wborn]

Upgrades PMD from 7.4.0 to 7.8.0

For release notes, see:

• https://docs.pmd-code.org/pmd-doc-7.8.0/pmd_release_notes.html
• https://docs.pmd-code.org/pmd-doc-7.8.0/pmd_release_notes_old.html

[wborn]

PMD 7.8.0 still works with Java 11, see: https://docs.pmd-code.org/pmd-doc-7.8.0/pmd_devdocs_building.html

Looks like the newer Jenkins versions using JDK 17 only support Maven projects using older JDKs via toolchains:

ERROR: ================================================================================
ERROR: Invalid project setup: Failed to load hudson.maven.AbstractMavenProcessFactory$ConfigureOriginalJDK
ERROR: [JENKINS-18403][JENKINS-28294] JDK 'OpenJDK 11' not supported to run Maven projects.
ERROR: Maven projects have to be launched with a Java version greater or equal to the minimum version required by the controller.
ERROR: Use the Maven JDK Toolchains (plugin) to build your maven project with an older JDK.
ERROR: Retrying with agent Java and setting compile/test properties to point to /var/jenkins_home/tools/hudson.model.JDK/OpenJDK_11.
ERROR: ================================================================================

GitHub Actions also builds using Java 11 without any issues.

Furthermore:

https://plugins.jenkins.io/maven-plugin/#plugin-content-risks

Risks

The Jenkins project recommends that users transition from the Maven job type to use Pipeline jobs or freestyle jobs. Stephen Connolly describes many of the reasons in his 2013 blog post, "Jenkins' Maven job type considered evil".

I'd personally rather spend my time on migrating everything to GitHub Actions. 😉