Enhancement: Use Php73 rule set

[localheinz]

This pull request

• uses the Php73 rule set
• runs make coding-standards

[codecov]

Codecov Report

Merging #531 (1dc38f2) into main (75cf0f0) will not change coverage.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##                main      #531   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
  Complexity        87        87           
===========================================
  Files             12        12           
  Lines            302       302           
===========================================
  Hits             302       302           

Impacted Files	Coverage Δ
src/DataProvider/StringProvider.php	100.00% <100.00%> (ø)
src/Exception/InvalidExcludeClassName.php	100.00% <100.00%> (ø)
src/Exception/NonExistentDirectory.php	100.00% <100.00%> (ø)
src/Exception/NonExistentExcludeClass.php	100.00% <100.00%> (ø)
src/Helper.php	100.00% <100.00%> (ø)

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