Ignore system package warnings in github actions.

.github/workflows/build_mac.yml

@@ -84,6 +84,7 @@ jobs:
         sudo installer -pkg ~/python.pkg -target /
         unlink /usr/local/bin/python || true
         ln -s /usr/local/bin/python3 /usr/local/bin/python
+        echo "[global]\nbreak-system-packages = true" > ~/.config/pip/pip.conf
     - uses: actions/cache@v4
       with:
         path: ~/Library/Caches/pip