Drupal 11 compatibility fixes for purge_users

Problem/Motivation

We are using the purge_users module on several of our websites that we want to migrate to Drupal 11.

Proposed resolution

• Implement a Drupal 11 compatible version of this module.
• Enable Gitlab CI.
• Fix PHP unit tests.
• Fix phpcs, phpstan and eslint warnings.
• Fix spelling (cspell).

Remaining tasks

Publish, review and validate MR.

Testing on Drupal 11

To test on Drupal 11, add the following lines to your composer.json repositories section:

  "repositories": [
    {
      "type": "vcs",
      "url": "https://git.drupalcode.org/issue/purge_users-3478176.git"
    },

and then run:

composer require drupal/purge_users:dev-3478176-drupal-11-compatibility