chore(deps): update dependency google-cloud-pubsub to v1.4.3 [(#3725)](GoogleCloudPlatform/python-docs-samples#3725)

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

Author: 3 people

samples/api-client/manager/requirements.txt

@@ -4,6 +4,6 @@ google-api-python-client==1.8.2
 google-auth-httplib2==0.0.3
 google-auth==1.14.2
 google-cloud-iot==1.0.0
-google-cloud-pubsub==1.4.2
+google-cloud-pubsub==1.4.3
 paho-mqtt==1.5.0
 pyjwt==1.7.1