Compatible with Django 3.0

[LKI]

Django 3.0 remove vendored library django.utils.six, ref: django 3.0 changelog

But we use it in rest_framework_mongoengine/serializers.py

So there will be an error:

ModuleNotFoundError: No module named 'django.utils.six'

[uoxiu]

@LKI Thanks for reporting, in the next few days we will fix this

[uoxiu]

@LKI fixed in the new release, 3.4.1

https://pypi.org/project/django-rest-framework-mongoengine/3.4.1/

[LKI]

Thanks!