WordPress 6.9 Compatibility

[colinmurphy]

Overview

WordPress 6.9 is scheduled to be released on 2nd of December 2025 - https://make.wordpress.org/core/6-9/

We need to test the current version of the Faust packages and the FaustWP Plugin to ensure that they are compatible with the latest version of WordPress 6.9.

Outcomes

1. Ensure the current Faust packages are compatible with WordPress 6.9
2. Ensure FaustWP plugin is compatible with WordPress 6.9
3. Update unit tests to include WordPress 6.9 and make 6.9 default WP version for tests
4. Create a release for FaustWP
5. Update FaustWP version for the WPE updater
6. Update FaustWP version on .org
7. Update FaustWP version on scaffold projects

[josephfusco]

Related: #2222