fix brew link error on mac CI

The github mac runner images added python 3.11 but, unlike 3.10, not via
brew. This causes brew install to fail with link conflict errors now
that boost-python3 switched over to 3.11. Workaround this, and future
python brew link errors, by overwriting all links for python packages.

Homebrew/homebrew-core@8c79089
https://github.com/orgs/Homebrew/discussions/3895
actions/setup-python#577
actions/runner-images#6459
actions/runner-images#6507
actions/runner-images#2322

.github/workflows/cmake.yml

@@ -43,6 +43,15 @@ jobs:
       - if: runner.os == 'macOS'
         name: Mac Dependencies
         run: |
+          # Unlink and re-link to prevent errors when github mac runner images
+          # install python outside of brew, for example:
+          # https://github.com/orgs/Homebrew/discussions/3895
+          # https://github.com/actions/setup-python/issues/577
+          # https://github.com/actions/runner-images/issues/6459
+          # https://github.com/actions/runner-images/issues/6507
+          # https://github.com/actions/runner-images/issues/2322
+          brew list -1 | grep python | while read formula; do brew unlink $formula; brew link --overwrite $formula; done
+
           brew update
           brew install boost boost-python3 gmp mpfr gpgme