PHP_CodeSniffer originally offered a number of "token groups" as static properties in the `Tokens` class to allow re-use of these groups across sniffs.
As of PHP_CodeSniffer 4.0.0, these static properties still exist, but are now (soft) deprecated in favour of class constants in the `Tokens` class for the same, which should create more stability, as this means the token groups can no longer be changed from within a(n external) sniff.

PHP_CodeSniffer related projects which still support both PHPCS 3.x as well as 4.x, will, for the time being, still need to use the static properties from the `Tokens` class.

Once a PHP_CodeSniffer related project has dropped support for PHPCS 3.x though, they can enforce the use of the class constants from the `Tokens` class by running this re-usable workflow in their CI.

* This workflow is particularly useful for repositories which have existing open PRs at the time of the PHPCS version drop and these open PRs should not re-introduce references to the static properties.
* This workflow can also be helpful for repositories which have contributors which contribute to a range of PHPCS related repos and for whom it would be very easy to overlook that they've used the "old-school" token group instead of the new-fangled token group constants.

In contrast to most of the other reusable workflows, this workflow does not work based on a configuration file.
One should only add a job calling this workflow to a project's CI once support for PHPCS 3.x has been dropped.

Includes adding documentation about this workflow to the `README` file.