ci(nightly): include backcompat in failure notifications

Author: Alenar

.github/workflows/nightly-dispatcher.yml

@@ -22,6 +22,6 @@ jobs:
 
   notify-on-failure:
     uses: ./.github/workflows/test-notify-on-failure.yml
-    needs: [docker-builds, aggregator-stress-test, test-client]
+    needs: [backward-compatibility, docker-builds, aggregator-stress-test, test-client]
     if: failure()
     secrets: inherit