chore(deps): update dependency google-cloud-bigquery to v2.20.0 (#199)

Author: renovate-bot

asset/snippets/snippets/requirements.txt

@@ -2,4 +2,4 @@ google-cloud-storage==1.38.0
 google-cloud-asset==2.2.0
 google-cloud-resource-manager==0.30.3
 google-cloud-pubsub==2.5.0
-google-cloud-bigquery==2.18.0
+google-cloud-bigquery==2.20.0