[CHORES] fix lint issue

riwayat/views.py

@@ -29,7 +29,7 @@ class RiwayatView(FlatMultipleModelAPIView):
     permission_classes = [IsAuthenticated]
 
     def get_serializer_class(self):
-        if getattr(self, 'swagger_fake_view', False):
+        if getattr(self, "swagger_fake_view", False):
             return PTSerializer
 
         raise NotImplementedError("must not call this")