upgrades: use setup-forgejo as a helper to setup docker & user

.forgejo/workflows/upgrade.yml

@@ -27,16 +27,15 @@ jobs:
         run: echo no hit
 
       - uses: https://code.forgejo.org/actions/checkout@v4
+      - uses: https://code.forgejo.org/actions/setup-forgejo@v2
+        with:
+          install-only: true
       - uses: https://code.forgejo.org/actions/setup-go@v4
         with:
           go-version: "1.21"
       - run: |
-          apt-get update -qq
-          apt-get -q install -qq -y docker.io
-          git config --add safe.directory '*'
-          adduser --quiet --comment forgejo --disabled-password forgejo
-          adduser forgejo docker
-          chown -R forgejo:forgejo .
+          set -x
+          forgejo-binary.sh ensure_user forgejo
       - run: |
           script=$(pwd)/forgejo/upgrades/test-upgrade.sh
           $script run dependencies