chore(deps): update dependency google/cloud-pubsub to v2 (#2002)

Author: renovate-bot

functions/tips_retry/composer.json

@@ -3,7 +3,7 @@
         "google/cloud-functions-framework": "^1.0.0"
     },
     "require-dev": {
-        "google/cloud-pubsub": "^1.29",
+        "google/cloud-pubsub": "^2.0",
         "google/cloud-logging": "^1.21"
     },
     "scripts": {