Enhancement: Add rule set for PHPUnit

[localheinz]

This PR

• adds a rule set for PHPUnit

[codecov]

Codecov Report

Merging #300 (57e4314) into main (0109e4a) will not change coverage.
The diff coverage is n/a.

@@             Coverage Diff             @@
##                main      #300   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
  Complexity         8         8           
===========================================
  Files              2         2           
  Lines             24        24           
===========================================
  Hits              24        24           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 0109e4a...57e4314. Read the comment docs.