ci: Ensure cleanup runs after notify completes

Without declaring it as a dependency the job can run in parallel and delete the workspace out from under the notify job.

Using format from this example: https://docs.github.com/en/actions/using-jobs/using-jobs-in-a-workflow#example-not-requiring-successful-dependent-jobs

.github/workflows/spectesting.yml

@@ -96,7 +96,7 @@ jobs:
   cleanup:
     runs-on: self-hosted
     name: Cleanup Post Vagrant-Spec Tests
-    needs: spec-tests
+    needs: [spec-tests, notify-on-success]
     if: always()
     steps:
       - name: Clean Packet