Use root after all, but mark submodule folders as safe

.github/workflows/build-plugin.yaml

@@ -42,14 +42,17 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: ghcr.io/qno/rack-plugin-toolchain-win-linux
-      options: --user 1001
+      options: --user root
     strategy:
       matrix:
         platform: [win-x64, lin-x64]
     steps:
       - uses: actions/checkout@v3
         with:
           submodules: recursive
+      - name: make submodule folders safe for git operations
+        run: |
+          git submodule foreach 'git config --global --add safe.directory $(pwd)'
       - uses: actions/cache@v3
         id: plugin-version-cache
         with: