Don't require enum34 in python >= 3.4

This fixes the build in distros which no longer provide python3-enum34.

Author: frozencemetery

setup.py

@@ -206,6 +206,13 @@ def gssapi_modules(lst):
                           re.sub(r'\.\. code-block:: \w+', '::',
                                  open('README.txt').read())))
 
+install_requires = [
+    'decorator',
+    'six'
+]
+if sys.version_info < (3, 4):
+    install_requires.append('enum34')
+
 setup(
     name='gssapi',
     version='1.1.3',
@@ -259,9 +266,5 @@ def gssapi_modules(lst):
         extension_file('password_add', 'gss_add_cred_with_password'),
     ]),
     keywords=['gssapi', 'security'],
-    install_requires=[
-        'enum34',
-        'decorator',
-        'six'
-    ]
+    install_requires=install_requires
 )