fix macOS CI

[christian-rauch]

Recently the brew installation on the macOS CI failed with:

Error: The `brew link` step did not complete successfully
The formula built, but is not symlinked into /usr/local
Could not symlink bin/2to3
Target /usr/local/bin/2to3
already exists. You may want to remove it:
  rm '/usr/local/bin/2to3'

To force the link and overwrite all conflicting files:
  brew link --overwrite python@3.12

To list all files that would be deleted:
  brew link --overwrite python@3.12 --dry-run

and other Python related symlinks in /usr/local/bin/.

It's not entirely clear why this happens now without any change to the install script but removing these symlinks just before running brew seems to solve the issue.