update phpcs.xml in repo

[arhimede]

https://github.com/mezzio/mezzio/blob/3.17.x/phpcs.xml

to reflect the latest version inherited from mezzio

[alexmerlin]

Issue is already fixed, I'm using it to fix another bug introduced by fixing this issue.
Based on my review, one of the tasks was to:

phpcs.xml.dist: make it identical with phpcs.xml

Accidentally, instead of phpcs.xml.dist, the contents of phpunit.xml.dist were replaced with the ones of phpcs.xml

The new tasks are:

• phpcs.xml.dist: make it identical with phpcs.xml
• revert phpunit.xml.dist to its original form