Update dependencies and Dockerfile versions for CI

[missionmike]

Description

This PR updates a few dependencies:

• PHP version in composer.json's require to minimum 8.1 to match the workflow matrix minimum.
• lucatime/wpbrowser to latest.
• PHP version in Dockerfile to 8.1
• XDebug version in Dockerfile to 3.3.1 to work with PHP 8.1 (see https://xdebug.org/docs/compat)

After updating the dependencies and Dockerfile, a few values needed to be set:

• ENV for XDebug coverage in Dockerfile
• WP values in local/config/wp-config.php file for Codeception. Without these values, there were errors and the run-codeception script would fail.

Testing

To test locally, checkout this branch, then delete the following files/folders from local:

Then, run:

• composer install
• docker-compose up -d --build --force-recreate
• composer run-codeception -- -- --coverage --coverage-xml
• composer run-phpunit -- -- --coverage-text

All should run successfully.

Example of passing CI: https://github.com/missionmike/wp-graphql-testcase/actions/runs/8649079504