Fix Mac OS GitHub workflow

Prior to this change, CI was failing with the following error:

    ==> Installing asciidoc dependency: python@3.11
    ==> Pouring python@3.11--3.11.3.monterey.bottle.tar.gz
    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@3.11

    To list all files that would be deleted:
      brew link --overwrite --dry-run python@3.11

Explicitly link with overwrite.

Signed-off-by: Lukas Fleischer <lfleischer@calcurse.org>

.github/workflows/make.yml

@@ -29,6 +29,7 @@ jobs:
     - name: Install dependencies (MacOS)
       run: |
         brew update
+        brew install --overwrite python
         brew install automake
         brew install asciidoc
         brew install gettext