Enhancement: Use Php73 rule set

[localheinz]

This pull request

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

[codecov]

Codecov Report

Merging #405 (c4eb4a0) into main (6a588b3) will not change coverage.
The diff coverage is 100.00%.

@@             Coverage Diff             @@
##                main      #405   +/-   ##
===========================================
  Coverage     100.00%   100.00%           
  Complexity        20        20           
===========================================
  Files              1         1           
  Lines             50        50           
===========================================
  Hits              50        50           

Impacted Files	Coverage Δ
src/Printer.php	100.00% <100.00%> (ø)

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