ci: fix more bench variance

[flying-sheep]

we don’t want to measure spinlocks

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.92%. Comparing base (af90028) to head (78530ad).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##              main     #220      +/-   ##
===========================================
- Coverage   100.00%   97.92%   -2.08%     
===========================================
  Files           21       21              
  Lines          579      579              
===========================================
- Hits           579      567      -12     
- Misses           0       12      +12     

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[codspeed]

Merging this PR will not alter performance

✅ 232 untouched benchmarks

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_{Comparing fix-bench-variance (78530ad) with main (af90028)}