Enhancement: Use ergebnis/phpstan-rules instead of localheinz/phpstan-rules

[localheinz]

This PR

• uses ergebnis/phpstan-rules instead of localheinz/phpstan-rules

[codecov]

Codecov Report

Merging #177 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             master   #177   +/-   ##
=======================================
  Coverage       100%   100%           
  Complexity      128    128           
=======================================
  Files            30     30           
  Lines           379    379           
=======================================
  Hits            379    379

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