Remove macos12 ahead of brownout

[atravitz]

Checklist

• Added a news entry

Developers certificate of origin

• I certify that this contribution is covered by the MIT License here and the Developer Certificate of Origin at https://developercertificate.org/.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.84%. Comparing base (bfc8df5) to head (61654be).
Report is 161 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1025      +/-   ##
==========================================
- Coverage   94.59%   92.84%   -1.76%     
==========================================
  Files         134      134              
  Lines        9940     9940              
==========================================
- Hits         9403     9229     -174     
- Misses        537      711     +174     

Flag	Coverage Δ
fast-tests	92.84% <ø> (?)
slow-tests	?

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