Warning: Options.vitual_fields deprecated in Django 2.0

[tonybolanyo]

When use mixer with Django and pytest, some warnings appear:

RemovedInDjango20Warning: Options.virtual_fields is deprecated, use private_fields instead.

[jgirardet]

do you plane to put it in a new release ?
Because actually we can't use mixer with django 2.0. it's not a warning , it gives an error.

def __load_fields(self):

>       for field in self.__scheme._meta.virtual_fields:
E       AttributeError: 'Options' object has no attribute 'virtual_fi
```elds'

[marazmiki]

The same thing. A couple of weeks ago I made a PR with Django 2.0 support, but @klen by some reasons tries to don't notice it. 🤔

Anyway, Django 2.0 just has been released, and I don't want to wait anymore. Let's remember old times when we were putting external dependencies into a "compat" directory :)

[Fingel]

This is a bit worrying. Back when we decided to use Mixer it looked like an actively developed project. Now thinking we probably should have stuck with FactoryBoy.