feat: add support for Python 3.9 (#111)

Also, add missing declaration of support for Python 3.8.

Closes #110.

noxfile.py

@@ -15,7 +15,6 @@
 from __future__ import absolute_import
 import os
 import shutil
-import sys
 
 # https://github.com/google/importlab/issues/25
 import nox  # pytype: disable=import-error
@@ -24,7 +23,7 @@
 
 
 def _greater_or_equal_than_36(version_string):
-    tokens = version_string.split('.')
+    tokens = version_string.split(".")
     for i, token in enumerate(tokens):
         try:
             tokens[i] = int(token)
@@ -72,13 +71,13 @@ def default(session):
         session.run(*pytest_args)
 
 
-@nox.session(python=["2.7", "3.5", "3.6", "3.7", "3.8"])
+@nox.session(python=["2.7", "3.5", "3.6", "3.7", "3.8", "3.9"])
 def unit(session):
     """Run the unit test suite."""
     default(session)
 
 
-@nox.session(python=["2.7", "3.5", "3.6", "3.7", "3.8"])
+@nox.session(python=["2.7", "3.5", "3.6", "3.7", "3.8", "3.9"])
 def unit_grpc_gcp(session):
     """Run the unit test suite with grpcio-gcp installed."""
 

setup.py

@@ -53,7 +53,7 @@
 version = {}
 with open(os.path.join(package_root, "google/api_core/version.py")) as fp:
     exec(fp.read(), version)
-version = version['__version__']
+version = version["__version__"]
 
 readme_filename = os.path.join(package_root, "README.rst")
 with io.open(readme_filename, encoding="utf-8") as readme_file:
@@ -91,6 +91,8 @@
         "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
         "Programming Language :: Python :: 3.7",
+        "Programming Language :: Python :: 3.8",
+        "Programming Language :: Python :: 3.9",
         "Operating System :: OS Independent",
         "Topic :: Internet",
     ],