Update tox.ini

Author: MacHu-GWU

tox.ini

@@ -6,7 +6,7 @@
 # content of: tox.ini , put in same dir as setup.py
 # for more info: http://tox.readthedocs.io/en/latest/config.html
 [tox]
-envlist = py27, py34, py35, py36
+envlist = py36, py37, py38, py39
 
 [testenv]
 deps =