Fix: Methods can be static

[localheinz]

This PR

• turns instance methods into static methods where possible

[codecov]

Codecov Report

Merging #421 into master will decrease coverage by 0.09%.
The diff coverage is 76.92%.

@@             Coverage Diff              @@
##             master     #421      +/-   ##
============================================
- Coverage     80.92%   80.82%   -0.10%     
  Complexity       41       41              
============================================
  Files             4        4              
  Lines           194      193       -1     
============================================
- Hits            157      156       -1     
  Misses           37       37              

Impacted Files	Coverage Δ	Complexity Δ
src/Command/NormalizeCommand.php	85.46% <76.92%> (-0.09%)	34.00 <15.00> (ø)

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