bump WordPress "tested up to" version 6.3

[jeffpaul]

Description of the Change

Merges the changes from #152 to the trunk branch to hopefully trigger the Readme Updater action and push the changes over to WP.org.

Relates to #150.

How to test the Change

Changelog Entry

n/a

Credits

n/a

Checklist:

• [x] I agree to follow this project's Code of Conduct.
• [x] I have updated the documentation accordingly.
• [ ] I have added tests to cover my change.
• [ ] All new and existing tests pass.

[peterwilsoncc]

🟢 Action ran successfully, updated on plugin repo page.

[jeffpaul]

Nice, now I wonder why it worked here but not on so many others?