packages: simplify the setup to use the same as upgrades

the packages tests control which Forgejo version they run against so
they can test a feature on version X+1 and not on version X

.forgejo/workflows/upgrade.yml

@@ -31,8 +31,11 @@ jobs:
         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 .
       - run: |
           script=$(pwd)/forgejo/upgrades/test-upgrade.sh