Replace StyleCI with PHP CS Fixer

[mspirkov]

Q	A
Is bugfix?	❌
New feature?	❌
Breaks BC?	❌
Fixed issues

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88.23%. Comparing base (06353dc) to head (616c0f0).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master      #88   +/-   ##
=========================================
  Coverage     88.23%   88.23%           
  Complexity       36       36           
=========================================
  Files             4        4           
  Lines            85       85           
=========================================
  Hits             75       75           
  Misses           10       10           

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