simplify setup.py branches (#3806)

diff --git a/setup.py b/setup.py
index d232e0b..a7e63bd 100644
--- a/setup.py
+++ b/setup.py
@@ -40,10 +40,8 @@
 ]
 setup_requirements = []
 
-if sys.version_info < (3, 4):
+if sys.version_info < (3,):
     requirements.append("enum34")
-
-if sys.version_info < (3, 3):
     requirements.append("ipaddress")
 
 if platform.python_implementation() == "PyPy":