remove py36 from classifiers in setup

Author: Kully

setup.py

@@ -158,7 +158,6 @@ def run(self):
           'Programming Language :: Python :: 3.3',
           'Programming Language :: Python :: 3.4',
           'Programming Language :: Python :: 3.5',
-          'Programming Language :: Python :: 3.6',
           'Topic :: Scientific/Engineering :: Visualization',
       ],
       license='MIT',