chore(deps): update dependency google-cloud-pubsub to v1.5.0 [(#3781)](GoogleCloudPlatform/python-docs-samples#3781)

Co-authored-by: Bu Sun Kim <[email protected]>

Author: renovate-bot

samples/api-client/manager/requirements.txt

@@ -4,6 +4,6 @@ google-api-python-client==1.8.3
 google-auth-httplib2==0.0.3
 google-auth==1.15.0
 google-cloud-iot==1.0.0
-google-cloud-pubsub==1.4.3
+google-cloud-pubsub==1.5.0
 paho-mqtt==1.5.0
 pyjwt==1.7.1