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/

[pyup-bot]

Closing this in favor of #15