Removed more testing of Python <3.5.
diff --git a/python/setup.py b/python/setup.py
index 77a6c4a..e531b89 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -254,7 +254,7 @@
     os.environ['PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION'] = 'cpp'
 
   # Keep this list of dependencies in sync with tox.ini.
-  install_requires = ['six>=1.9']
+  install_requires = []
 
   setup(
       name='protobuf',