Update django to 2.0.5

[pyup-bot]

This PR updates django from 2.0.4 to 2.0.5.

Changelog

### 2.0.5 ``` ========================== *May 1, 2018* Django 2.0.5 fixes several bugs in 2.0.4. Bugfixes ======== * Corrected the import paths that ``inspectdb`` generates for ``django.contrib.postgres`` fields (:ticket:`29307`). * Fixed a regression in Django 1.11.8 where altering a field with a unique constraint may drop and rebuild more foreign keys than necessary (:ticket:`29193`). * Fixed crashes in ``django.contrib.admindocs`` when a view is a callable object, such as ``django.contrib.syndication.views.Feed`` (:ticket:`29296`). * Fixed a regression in Django 1.11.12 where ``QuerySet.values()`` or ``values_list()`` after combining an annotated and unannotated queryset with ``union()``, ``difference()``, or ``intersection()`` crashed due to mismatching columns (:ticket:`29286`). ========================== ```

Links

- PyPI: https://pypi.org/project/django - Changelog: https://pyup.io/changelogs/django/ - Homepage: https://www.djangoproject.com/

[coveralls]

Coverage remained the same at 99.503% when pulling e6c42eb83a55dfa68cd62dddc6326e297b3638f2 on pyup-update-django-2.0.4-to-2.0.5 into 459fa942a49f1d3c571e790c81ff82beab20f34c on master.

[coveralls]

Coverage remained the same at 99.503% when pulling bd31fa80aa1b11198014121730284af2b01b5ebf on pyup-update-django-2.0.4-to-2.0.5 into bef43c1e256434a6d0e1d65840d13bb7d8b00b6b on master.