Fix versions.

Author: yxd-hde

setup.py

@@ -45,7 +45,7 @@ def run_tests(self):
       packages=find_packages(exclude=['examples', 'tests']),
       include_package_data=True,
       zip_safe=False,
-      python_requires='>=2.7 >=3.6',
+      python_requires='>=2.7,!=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, !=3.5.*, <4',
       tests_require=['pytest'],
       cmdclass={'test': PyTest},
       install_requires=['boto3'],