Update a list of supported Python version

Author: asvetlov

setup.py

@@ -47,9 +47,10 @@ def read(f):
           'Intended Audience :: Developers',
           'Programming Language :: Python',
           'Programming Language :: Python :: 3',
-          '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',
           'Development Status :: 5 - Production/Stable',
           'Topic :: Internet :: WWW/HTTP',
           'Framework :: AsyncIO',