Use registry token secret for image publishing

.gitea/workflows/docker.yml

@@ -20,7 +20,7 @@ jobs:
       - name: Log in to Gitea Container Registry
         env:
           REGISTRY_USERNAME: ${{ gitea.actor }}
-          REGISTRY_TOKEN: ${{ secrets.GITEA_TOKEN }}
+          REGISTRY_TOKEN: ${{ secrets.REGISTRY_TOKEN }}
         run: |
           printf '%s' "$REGISTRY_TOKEN" |
             docker login git.anchorhost.eu --username "$REGISTRY_USERNAME" --password-stdin