Auto-update dependencies. [(#1846)](GoogleCloudPlatform/python-docs-samples#1846)

ACK, merging.

Author: dpebot

samples/snippets/requirements.txt

@@ -1,5 +1,5 @@
 google-cloud-dlp==0.9.0
-google-cloud-storage==1.10.0
-google-cloud-pubsub==0.37.2
-google-cloud-datastore==1.7.0
-google-cloud-bigquery==1.5.0
+google-cloud-storage==1.13.0
+google-cloud-pubsub==0.38.0
+google-cloud-datastore==1.7.1
+google-cloud-bigquery==1.7.0