chore(deps): update dependency google-cloud-pubsub to v2.4.0 (#154)

Author: renovate-bot

asset/snippets/snippets/requirements.txt

@@ -1,5 +1,5 @@
 google-cloud-storage==1.36.1
 google-cloud-asset==2.2.0
 google-cloud-resource-manager==0.30.3
-google-cloud-pubsub==2.3.0
+google-cloud-pubsub==2.4.0
 google-cloud-bigquery==2.9.0