Update django to 2.2.10

[pyup-bot]

This PR updates Django from 2.2.9 to 2.2.10.

Changelog

2.2.10

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

*February 3, 2020*

Django 2.2.10 fixes a security issue in 2.2.9.

CVE-2020-7471: Potential SQL injection via ``StringAgg(delimiter)``
===================================================================

:class:`~django.contrib.postgres.aggregates.StringAgg` aggregation function was
subject to SQL injection, using a suitably crafted ``delimiter``.


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

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 #1770