Bump the required Python versions in setup.py.

Author: clokep

setup.py

@@ -40,5 +40,5 @@ def long_description():
     install_requires=[
         'django>=1.11',
     ],
-    python_requires=">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*",
+    python_requires=">=3.5",
 )