workflows: Add label on CI check failures

Automatically add label so broken PR wont go to staging

Signed-off-by: Denys Fedoryshchenko <denys.f@collabora.com>

Author: nuclearcat

.github/workflows/main.yml

@@ -48,4 +48,19 @@ jobs:
       - name: Run basic yaml validation
         run: |
           python tests/validate_yaml.py
-        
+  on-fail:
+    if: failure() && github.event_name == 'pull_request'
+    runs-on: ubuntu-latest
+    needs: check
+    steps:
+      - name: Add label to PR
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const label = 'staging-skip';
+            github.rest.issues.addLabels({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.issue.number,
+              labels: [label]
+            });