Update mirror workflow to exclude upstream workflows

Install git-filter-repo and filter out workflows

Author: teo

.github/workflows/mirror.yml

@@ -17,8 +17,8 @@ jobs:
           git clone https://codeberg.org/Calamares/calamares.git mirror
           cd mirror
 
-          # Remove upstream workflows so they are not pushed
-          rm -rf .github/workflows
+          pip install git-filter-repo
+          git filter-repo --path .github/workflows --invert-paths
 
           # Set GitHub as push target using Actions token
           git remote add github "https://${GITHUB_ACTOR}:${{ secrets.GITHUB_TOKEN }}@github.com/teo/calamares.git"