Remove Python version check

We require Python 3 now, so no need for this check.

tests/test_websocketproxy.py

@@ -115,7 +115,6 @@ class ProxyRequestHandlerTestCase(unittest.TestCase):
         self.assertEqual(self.handler.server.target_host, "somehost")
         self.assertEqual(self.handler.server.target_port, "blah")
 
-    if sys.version_info >= (2,7):
     def test_asymmetric_jws_token_plugin(self):
         key = jwt.JWK()
         private_key = open("./tests/fixtures/private.pem", "rb").read()