Update django to 1.11.9

[pyup-bot]

There's a new version of Django available.
You are currently using 1.11.8. I have updated it to 1.11.9

These links might come in handy: PyPI | Changelog | Homepage

Changelog

1.11.9

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

January 1, 2018

Django 1.11.9 fixes several bugs in 1.11.8.

Bugfixes

• Fixed a regression in Django 1.11 that added newlines between MultiWidget's
  subwidgets (:ticket:28890).

• Fixed incorrect class-based model index name generation for models with
  quoted db_table (:ticket:28876).

• Fixed incorrect foreign key constraint name for models with quoted
  db_table (:ticket:28876).

• Fixed a regression in caching of a GenericForeignKey when the referenced
  model instance uses more than one level of multi-table inheritance
  (:ticket:28856).

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

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖

[coveralls]

Coverage remained the same at 92.593% when pulling f4dec57 on pyup-update-django-1.11.8-to-1.11.9 into 11061eb on master.