Replace macos-12 runners with macos-15

[mborland]

macOS-12 is pending removal and 15 was just added

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 94.54%. Comparing base (35e86d9) to head (ebf2066).
Report is 2 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #229   +/-   ##
========================================
  Coverage    94.54%   94.54%           
========================================
  Files           67       67           
  Lines         8490     8490           
========================================
  Hits          8027     8027           
  Misses         463      463           

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