fix(ci): use git diff --quiet instead of git status for umbrella check

git status --porcelain also reports untracked files — cargo install zepter
writes .cargo/ inside the project dir on shared GitLab runners, causing
false positives. git diff --quiet only checks tracked file changes.

.gitlab-ci.yml

@@ -132,11 +132,8 @@ check-umbrella:
       zepter run default
       cargo +nightly fmt -p pezkuwi-sdk
     - |
-      if [ -n "$(git status --porcelain)" ]; then
+      if ! git diff --quiet; 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