Updated dependencies and supported PHP/WordPress

[danielmorell]

Description of the change

This PR handles updating dependencies including system dependencies and compatability. This will be released as version 3.2.0.

Notable Changes:

• Removed support for PHP 8.1 (it reached end of life Dec 31 2025)
• Removed support for WordPress 6.5.
• Added support for WordPress 7.0.
• Updated humbug/php-scoper which supports PHP 8.5. This allows us to run the plugin build and scope tests against PHP 8.5.
• PHPUnit updated to 12. So we can replace docblock @ tags with PHP attributes in the test suite.

Type of change

• Maintenance

Related issues

None

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers assigned
• Issue from task tracker has a link to this pull request
• Changes have been reviewed by at least one other engineer