Fix one issue

rest_framework_nested/relations.py

@@ -6,20 +6,19 @@
 """
 from __future__ import unicode_literals
 from functools import reduce  # import reduce from functools for compatibility with python 3
-from typing import Any, Union, TypeVar
+from typing import Any, Generic, Union, TypeVar
 
-import rest_framework.relations
 from django.core.exceptions import ObjectDoesNotExist
 from django.db.models import Model
-from rest_framework.relations import ObjectValueError, ObjectTypeError
+from rest_framework.relations import HyperlinkedRelatedField, ObjectValueError, ObjectTypeError
 from rest_framework.exceptions import ValidationError
 from rest_framework.request import Request
 
 
 T_Model = TypeVar('T_Model', bound=Model)
 
 
-class NestedHyperlinkedRelatedField(rest_framework.relations.HyperlinkedRelatedField[T_Model]):
+class NestedHyperlinkedRelatedField(HyperlinkedRelatedField, Generic[T_Model]):
     lookup_field = 'pk'
     parent_lookup_kwargs = {
         'parent_pk': 'parent__pk'