Updates the configuration file filename on the Create a Network of WordPress Sites multisite setup page to use config/application.php instead of wp-config.php. Also adds a Composer script to update the platform PHP version in the composer.json file to match the version of PHP in the pantheon.yml. For more information, see: https://docs.pantheon.io/release-notes/2024/06/pantheon-mu-plugin-1-4-4-wordpress-composer-managed-update
Release PR for WPCM update.
Updates changelog and commit message: