Bump django from 1.11.23 to 1.11.28

Bumps [django](https://github.com/django/django) from 1.11.23 to 1.11.28.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@1.11.23...1.11.28)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements.txt

@@ -1,5 +1,5 @@
 # Django itself
-Django==1.11.23
+Django==1.11.28
 
 # Additional Django Apps
 django-forms-bootstrap==3.0.1