chore(deps): update dependency google-cloud-bigquery-storage to v2.6.0 (#743)

Author: renovate-bot

samples/geography/requirements.txt

@@ -1,4 +1,4 @@
 geojson==2.5.0
 google-cloud-bigquery==2.20.0
-google-cloud-bigquery-storage==2.5.0
+google-cloud-bigquery-storage==2.6.0
 Shapely==1.7.1

samples/snippets/requirements.txt

@@ -1,5 +1,5 @@
 google-cloud-bigquery==2.20.0
-google-cloud-bigquery-storage==2.5.0
+google-cloud-bigquery-storage==2.6.0
 google-auth-oauthlib==0.4.4
 grpcio==1.38.1
 ipython==7.16.1; python_version < '3.7'