[CI] Fix MacOS builds in Github Actions

[uilianries]

The Github actions is moving their MacOS versions supported and XCode versions as well: https://github.com/actions/runner-images/tree/main?tab=readme-ov-file#available-images

This PR drops Macos 11 and 12 (both deprecated) and run only new versions. Plus, I dropped Debug builds, because Mac build in Github actions are most expansive (they take more time to be available).

The Cmake minimum change is due compatibility warning from CMake itself: https://github.com/uilianries/json/actions/runs/12534415695/job/34955186794#step:5:7

The CMake version 3.10 is from 2017, so I doubt users will complain about it.

[uilianries]

Macos is passing now: https://github.com/taocpp/json/actions/runs/12534486214/job/34955351051?pr=158

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.01%. Comparing base (821c7d8) to head (c4e9719).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #158   +/-   ##
=======================================
  Coverage   74.01%   74.01%           
=======================================
  Files         257      257           
  Lines        9191     9191           
  Branches      804      804           
=======================================
  Hits         6803     6803           
  Misses       1785     1785           
  Partials      603      603           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.