chore(deps): update dependency matplotlib to v3.3.0 [(#4310)](GoogleCloudPlatform/python-docs-samples#4310)

Author: renovate-bot

samples/snippets/requirements.txt

@@ -1,5 +1,5 @@
 google-cloud-bigquery[pandas]==1.25.0
 google-auth-oauthlib==0.4.1
 ipython==7.16.1
-matplotlib==3.2.2
+matplotlib==3.3.0
 pytz==2020.1