Update django to 2.2.7

[pyup-bot]

This PR updates django from 2.2.5 to 2.2.7.

Changelog

2.2.7

==========================

*November 4, 2019*

Django 2.2.7 fixes several bugs in 2.2.6.

Bugfixes
========

* Fixed a crash when using a ``contains``, ``contained_by``, ``has_key``,
``has_keys``, or ``has_any_keys`` lookup on
:class:`~django.contrib.postgres.fields.JSONField`, if the right or left hand
side of an expression is a key transform (:ticket:`30826`).

* Prevented :option:`migrate --plan` from showing that ``RunPython`` operations
are irreversible when ``reverse_code`` callables don't have docstrings or
when showing a forward migration plan (:ticket:`30870`).

* Fixed migrations crash on PostgreSQL when adding an
:class:`~django.db.models.Index` with fields ordering and
:attr:`~.Index.opclasses` (:ticket:`30903`).

* Restored the ability to override
:meth:`~django.db.models.Model.get_FOO_display` (:ticket:`30931`).


==========================

2.2.6

==========================

*October 1, 2019*

Django 2.2.6 fixes several bugs in 2.2.5.

Bugfixes
========

* Fixed migrations crash on SQLite when altering a model containing partial
indexes (:ticket:`30754`).

* Fixed a regression in Django 2.2.4 that caused a crash when filtering with a
``Subquery()`` annotation of a queryset containing
:class:`~django.contrib.postgres.fields.JSONField` or
:class:`~django.contrib.postgres.fields.HStoreField` (:ticket:`30769`).


==========================

Links

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

[coveralls]

Pull Request Test Coverage Report for Build 1231

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 99.275%

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Totals
Change from base Build 1198:	0.0%
Covered Lines:	2191
Relevant Lines:	2207

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💛 - Coveralls

[pyup-bot]

Closing this in favor of #297