Update tested WordPress version to 6.5

[felixarntz]

Summary

This PR updates Performance Lab and its standalone plugins' tested up to WordPress version to the upcoming 6.5. It also bumps the standalone plugin versions accordingly.

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Co-authored-by: felixarntz <flixos90@git.wordpress.org>
Co-authored-by: thelovekesh <thelovekesh@git.wordpress.org>
Co-authored-by: westonruter <westonruter@git.wordpress.org>

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[westonruter]

It's too bad a version bump is needed to do just this. Previously I've just manually bumped the version in the readme.txt of the latest SVN tag as a way to avoid having to do a release.

[felixarntz]

Agreed. I think there's a way to automate this too via GitHub workflow somehow. But until we have this, probably fine to do this.