ci: skip pip error externally managed environment

.github/workflows/main.yaml

@@ -36,7 +36,7 @@ jobs:
         run: sudo apt-get install -y python3-dev python3-pip shellcheck reuse
       # gitlint is available on Debian but Ubuntu has an older version.
       - name: Install pip packages
-        run: pip3 install salt-lint gitlint
+        run: pip3 install --break-system-packages salt-lint gitlint
       - uses: actions/checkout@v4
         with:
           fetch-depth: 0