Class file versions 65 in linkage checker

[jvmakine]

I love the Linkage Checker! However, I am now working in a large project compiling to class file version 65 with java 21. This does not seem to be supported at https://github.com/GoogleCloudPlatform/cloud-opensource-java/blob/a4649811a02dc6eb2f6b67626004b8424c1ae58b/dependencies/src/main/java/com/google/cloud/tools/opensource/classpath/ClassDumper.java#L179

I would love to have the supported class file versions to be bumped to a more recent version so I can use this amazing tool in my current project!