chore(deps): update dependency google-auth to v2.20.0 (#2156)

Author: renovate-bot

samples/compute/requirements.txt

@@ -1,3 +1,3 @@
 google-api-python-client==2.89.0
-google-auth==2.19.1
+google-auth==2.20.0
 google-auth-httplib2==0.1.0