feat: add support for python 3.10 (googleapis#1557)

Author: parthea

README.md

@@ -97,7 +97,7 @@ virtualenv <your-env>
 
 ## Supported Python Versions
 
-Python 3.6, 3.7, 3.8, and 3.9 are fully supported and tested. This library may work on later versions of 3, but we do not currently run tests against those versions.
+Python 3.6, 3.7, 3.8, 3.9 and 3.10 are fully supported and tested. This library may work on later versions of 3, but we do not currently run tests against those versions.
 
 ## Unsupported Python Versions
 

noxfile.py

@@ -45,7 +45,7 @@ def lint(session):
     )
 
 
-@nox.session(python=["3.6", "3.7", "3.8", "3.9"])
+@nox.session(python=["3.6", "3.7", "3.8", "3.9", "3.10"])
 @nox.parametrize(
     "oauth2client",
     [

setup.py

@@ -74,6 +74,7 @@
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
         "Development Status :: 5 - Production/Stable",
         "Intended Audience :: Developers",
         "License :: OSI Approved :: Apache Software License",