fix: lowercase docker tag in CI workflow

.gitea/workflows/ci.yml

@@ -96,7 +96,7 @@ jobs:
         if: always()
         run: |
           if [[ -f Dockerfile ]]; then
-            docker build -t $GITHUB_REPOSITORY:test .
+            docker build -t $(echo $GITHUB_REPOSITORY | tr '[:upper:]' '[:lower:]'):test .
           else
             echo "No Dockerfile found, skipping docker build"
           fi