Update dependency google-auth-httplib2 to v0.0.4 [(#4255)](GoogleCloudPlatform/python-docs-samples#4255)

Co-authored-by: Takashi Matsuo <tmatsuo@google.com>

Author: renovate-bot

samples/api-client/manager/requirements.txt

@@ -1,7 +1,7 @@
 cryptography==2.9.2
 flaky==3.7.0
 google-api-python-client==1.9.3
-google-auth-httplib2==0.0.3
+google-auth-httplib2==0.0.4
 google-auth==1.18.0
 google-cloud-iot==1.0.0
 google-cloud-pubsub==1.6.1