Plugin: Bump minimum required WordPress version to 6.5

[Mamaduka]

What?

Similar to #60780.
Related to #64096.

Bumps the "Required WP version" field to 6.5, and the "Tested up to" field to 6.6. It also updates the performance test base hash.

Why?

See https://developer.wordpress.org/block-editor/explanations/architecture/performance/#update-the-reference-commit

How?

Testing Instructions

• CI checks should be green.
• Confirm that new commit SHA matches guidelines.

[talldan]

LGTM, thanks for handling this.

[github-actions]

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Co-authored-by: Mamaduka <mamaduka@git.wordpress.org>
Co-authored-by: talldan <talldanwp@git.wordpress.org>
Co-authored-by: ramonjd <ramonopoly@git.wordpress.org>
Co-authored-by: youknowriad <youknowriad@git.wordpress.org>

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[Mamaduka]

Thanks, @talldan!

@youknowriad, can you confirm that the new perf SHA looks okay to you?

[ramonjd]

LGTM