fix(workflows): fix commit ID error in push events mode (#9231)

Signed-off-by: rongyichang <rongyichang@xiaomi.com>

.github/workflows/ccpp.yml

@@ -143,6 +143,9 @@ jobs:
           echo "Merge-base: $MB"
           python scripts/check_gcov_coverage.py --commit="${MB}...${{ github.event.pull_request.head.sha }}"
         else
+          # For push events, fetch enough history to resolve HEAD^
+          git fetch --no-tags --prune --depth=2 origin
+          echo "Using HEAD commit for push event"
           python scripts/check_gcov_coverage.py --commit=HEAD
         fi
     - name: Archive screenshot errors