Add PHP 8.4 Compatibility

[n7studios]

Summary

Runs tests against PHP 8.4, adding compatibility to fix the Implicitly marking parameter $value as nullable is deprecated, the explicit nullable type must be used instead deprecated notice, by using the Union Type on null parameters.

Testing

Existing tests pass.

Checklist

• I have written a test and included it in this PR
• I have run all tests and they pass
• The code passes when running the PHP CodeSniffer
• The code passes when running PHPStan
• I have assigned a reviewer or two to review this PR (if you're not sure who to assign, we can do this step for you)

[corydhmiller]

👍