convert enum name without breaking things on platforms without enum

graphene_django/converter.py

@@ -1,5 +1,3 @@
-import enum
-
 from django.db import models
 from django.utils.encoding import force_text
 
@@ -19,8 +17,7 @@ singledispatch = import_single_dispatch()
 
 
 def convert_choice_name(name):
-    if isinstance(name, enum.Enum):
-        name = name.name
+    name = getattr(name, 'name', name)
     name = to_const(force_text(name))
     try:
         assert_valid_name(name)