added python 3.9 classifier

Author: auvipy

setup.py

@@ -223,6 +223,7 @@ def run_setup(with_extensions=True):
             'Programming Language :: Python :: 3.6',
             'Programming Language :: Python :: 3.7',
             'Programming Language :: Python :: 3.8',
+            'Programming Language :: Python :: 3.9',
             'Programming Language :: Python :: Implementation :: CPython',
             'Programming Language :: Python :: Implementation :: PyPy',
             'Operating System :: Microsoft :: Windows',