chore: release 1.8.1 (#868)

diff --git a/setup.py b/setup.py
index 4174362..60974fb 100644
--- a/setup.py
+++ b/setup.py
@@ -52,7 +52,7 @@
 with io.open(readme_filename, encoding="utf-8") as readme_file:
     readme = readme_file.read()
 
-version = "1.8.0"
+version = "1.8.1"
 
 setup(
     name="google-api-python-client",