chore(deps): update dependency grpcio to v1.39.0 (#796)

Author: renovate-bot

samples/snippets/requirements.txt

@@ -1,7 +1,7 @@
 google-cloud-bigquery==2.22.0
 google-cloud-bigquery-storage==2.6.0
 google-auth-oauthlib==0.4.4
-grpcio==1.38.1
+grpcio==1.39.0
 ipython==7.16.1; python_version < '3.7'
 ipython==7.17.0; python_version >= '3.7'
 matplotlib==3.3.4; python_version < '3.7'