Add PHP-CS-Fixer Github action

[robbinjanssen]

Description

Adds a php-cs-fixer action to lint the code instead of styleci.

Checklist:

Go over all the following points, and put an x in all the boxes that apply.

Please, please, please, don't send your pull request until all of the boxes are ticked. Once your pull request is created, it will trigger a build on our continuous integration server to make sure your tests pass.

• I have read the CONTRIBUTING document.
• My pull request addresses exactly one patch/feature.
• My pull request contains a title that can be used as a release note.
• I have added the appropriate labels to my pull request (e.g. breaking-change, new-feature, bugfix).
• I have created a branch for this patch/feature.
• Each individual commit in the pull request is meaningful.
• I have added tests to cover my changes.
• If my change requires a change to the documentation, I have updated it accordingly.

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