Issue with using TenantModel in DjangoRestFramework viewsets

To use TenantModel with Django Rest Framework's ViewSets, the following refactor was necessary:
```python
# before
class MyModelViewSet(GenericViewSet):
queryset = MyModel.objects.all()
```
```python
# after
class MyModelViewSet(GenericViewSet):
def get_queryset(self):
return MyModel.objects.all()
```