Auto-update dependencies. [(#1980)](GoogleCloudPlatform/python-docs-samples#1980)

* Auto-update dependencies.

* Update requirements.txt

* Update requirements.txt

Author: dpebot

samples/snippets/requirements.txt

@@ -2,4 +2,4 @@ google-cloud-dlp==0.10.0
 google-cloud-storage==1.13.2
 google-cloud-pubsub==0.39.1
 google-cloud-datastore==1.7.3
-google-cloud-bigquery==1.8.1
+google-cloud-bigquery==1.9.0