Avoid annotation processor warning

[Bananeweizen]

Java 21+ warns about active annotation processors, unless the compiler has been explicitly configured to accept them.

See https://bugs.openjdk.org/browse/JDK-8310061

What's changed?

Remove this warning from the build process, when running Maven on Java 21+:

Doesn't have any side effects on older JDKs.

Further references: https://inside.java/2023/07/29/quality-heads-up/ or https://github.com/khmarbaise/jdk21

[timtebeek]

Thanks for the hint, fix and helpful links! Looks like we might also need to bump the GitHub Actions Java version to get this to work.

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.11.0:compile (default-compile) on project rewrite-maven-plugin: Fatal error compiling: error: invalid flag: -proc:full -> [Help 1]
https://github.com/openrewrite/rewrite-maven-plugin/actions/runs/7072162982/job/19250685994?pr=673#step:4:43

[timtebeek]

Ok seems we depend on this one to get the tests going

• Drop HasSourcePath in favor of FindSourceFiles rewrite#3755