Remove infection and update to PHPUnit 11

[acelaya]

Infection has become a somewhat useful tool, but one mostly ignored in the project.

On the other hand, when it fails due to low MSI, it usually leads to reducing required MSI and going on.

Additionally, it usually delays adopting new PHPUnit major versions, due to overlapping dependencies with mismatching versions.

This PR removes infection all together, and updates to PHPUnit 11

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (a43b380) 72.61% compared to head (d999601) 72.28%.

Additional details and impacted files

@@             Coverage Diff              @@
##               main      #32      +/-   ##
============================================
- Coverage     72.61%   72.28%   -0.33%     
  Complexity       22       22              
============================================
  Files             5        5              
  Lines            84       83       -1     
============================================
- Hits             61       60       -1     
  Misses           23       23              

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