fixed the wrong env name

.forgejo/workflows/container-build.yml

@@ -18,7 +18,7 @@ jobs:
         run: |
           skopeo login -u 'user' -p "${{ secrets.DOCKER_TOKEN }}" ${GITHUB_SERVER_URL}
           server=${GITHUB_SERVER_URL//https:/docker:}
-          for tag in latest $GITHUB_TAG_NUMBER ; do
+          for tag in latest $GITHUB_RUN_NUMBER ; do
               echo pushing image to "${server}/${GITHUB_REPOSITORY}:${tag}"
               skopeo copy -q -a --dest-precompute-digests dir:image "${server}/${GITHUB_REPOSITORY}:${tag}"
           done