GHA: Use GCC 13 for coverage

[Flamefire]

Test

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.41%. Comparing base (756e3dc) to head (86b2e8c).
⚠️ Report is 77 commits behind head on develop.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #188      +/-   ##
===========================================
- Coverage    99.45%   99.41%   -0.05%     
===========================================
  Files           34       34              
  Lines         3319     3592     +273     
===========================================
+ Hits          3301     3571     +270     
- Misses          18       21       +3     

see 25 files with indirect coverage changes

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