Fix super() usage in python 2.7

Author: bellini666

graphene_django/filter/fields.py

@@ -55,7 +55,12 @@ def filtering_args(self):
     def resolve_queryset(
         cls, connection, iterable, info, args, filtering_args, filterset_class
     ):
-        qs = super().resolve_queryset(connection, iterable, info, args)
+        qs = super(DjangoFilterConnectionField, cls).resolve_queryset(
+            connection,
+            iterable,
+            info,
+            args,
+        )
         filter_kwargs = {k: v for k, v in args.items() if k in filtering_args}
         return filterset_class(
             data=filter_kwargs, queryset=qs, request=info.context