Bump django from 1.11.25 to 1.11.26

Bumps [django](https://github.com/django/django) from 1.11.25 to 1.11.26.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@1.11.25...1.11.26)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

requirements.txt

@@ -1,5 +1,5 @@
 coverage==4.5.4
-Django==1.11.25 # pyup: <2.0
+Django==1.11.26 # pyup: <2.0
 django-debug-toolbar==2.0
 docutils==0.15.2
 freezegun==0.3.12