Use phpstan.dist.neon instead of phpstan.neon

[thomascorthals]

How I should've done it in #1147.

H/T: @thePanz

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.15%. Comparing base (9cdf3dd) to head (798dae6).
Report is 15 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1149      +/-   ##
==========================================
+ Coverage   97.75%   98.15%   +0.39%     
==========================================
  Files         400      404       +4     
  Lines       10524    10663     +139     
==========================================
+ Hits        10288    10466     +178     
+ Misses        236      197      -39     

Flag	Coverage Δ
unittests	98.15% <ø> (+0.39%)	⬆️

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