Remove Python 2 in CLASSIFIERS

Follow-up to gh-26330

Author: gfyoung

setup.py

@@ -214,9 +214,7 @@ def build_extensions(self):
     'Operating System :: OS Independent',
     'Intended Audience :: Science/Research',
     'Programming Language :: Python',
-    'Programming Language :: Python :: 2',
     'Programming Language :: Python :: 3',
-    'Programming Language :: Python :: 2.7',
     'Programming Language :: Python :: 3.5',
     'Programming Language :: Python :: 3.6',
     'Programming Language :: Python :: 3.7',