chore(deps): update dependency google-cloud-bigquery to v2.20.0 (#161)

Author: renovate-bot

dlp/snippets/requirements.txt

@@ -2,4 +2,4 @@ google-cloud-dlp==3.1.0
 google-cloud-storage==1.38.0
 google-cloud-pubsub==2.5.0
 google-cloud-datastore==2.1.3
-google-cloud-bigquery==2.18.0
+google-cloud-bigquery==2.20.0