chore: release 2.20.0 (#1517)

Co-authored-by: release-please[bot] <55107282+release-please[bot]@users.noreply.github.com>
diff --git a/setup.py b/setup.py
index 688fe4b..b6bcdaf 100644
--- a/setup.py
+++ b/setup.py
@@ -51,7 +51,7 @@
 with io.open(readme_filename, encoding="utf-8") as readme_file:
     readme = readme_file.read()
 
-version = "2.19.1"
+version = "2.20.0"
 
 setup(
     name="google-api-python-client",