debug(ci): show changed files and diff in check-umbrella failure

.gitlab-ci.yml

@@ -134,6 +134,9 @@ check-umbrella:
     - |
       if [ -n "$(git status --porcelain)" ]; then
         echo "❌ Umbrella crate is out of sync. Run: python3 scripts/generate-umbrella.py --sdk . --version <VERSION> && zepter run default"
+        echo "--- Changed files ---"
+        git status --porcelain
+        echo "--- Diff ---"
         git diff
         exit 1
       fi