Fix: Update composer.json to run the test suites

[hbhalodia]

• Update composer.json to add phpunit version 8.5 and 9.
• Add doctrine/instantiator to instantiate objects. (Resolved unit test with php 8.2 WP latest and php 8.2 wp 6.2)

[hbhalodia]

Hi @dmsnell, Have updated the composer dependencies and its working as expected. The only tests are failing because of compatibility issue for PHPUnit version and WP compatibility.

I have tried multiple things in PR - #258, But was unable to resolve the test failures, but yes have resolved the issue with composer.json which were not installed as per the comment - #254 (comment)

Let me know if we can move forward with this, merge and rebase the PR - #254?

Or to fix the test, what can be done to resolve unit test with less than WP 5.7 version added in tests.yml? should we skip those, remove or is there any alternatives?