ci: Set safe directory

Author: bbhtt

.github/workflows/update.yaml

@@ -17,6 +17,10 @@ jobs:
         with:
           ref: ${{ matrix.branch }}
 
+      - name: Set safe directory
+        run: |
+          git config --global --add safe.directory "/github/workspace"
+
       - uses: docker://ghcr.io/flathub/flatpak-external-data-checker:latest
         env:
           GIT_AUTHOR_NAME: flathubbot