fix(deps): update dependency @google-cloud/pubsub to v3.3.0

Author: renovate-bot

background/package.json

@@ -15,7 +15,7 @@
   },
   "dependencies": {
     "@google-cloud/firestore": "^5.0.0",
-    "@google-cloud/pubsub": "3.1.0",
+    "@google-cloud/pubsub": "3.3.0",
     "@google-cloud/storage": "^6.0.0",
     "express": "^4.16.4"
   },