Bump django-debug-toolbar from 1.8 to 1.11.1

Bumps [django-debug-toolbar](https://github.com/jazzband/django-debug-toolbar) from 1.8 to 1.11.1.
- [Release notes](https://github.com/jazzband/django-debug-toolbar/releases)
- [Changelog](https://github.com/jazzband/django-debug-toolbar/blob/1.11.1/docs/changes.rst)
- [Commits](https://github.com/jazzband/django-debug-toolbar/compare/1.8...1.11.1)

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

requirements.txt

@@ -1,5 +1,5 @@
 django>=1.11,<1.12
-django-debug-toolbar==1.8
+django-debug-toolbar==1.11.1
 gunicorn==19.5.0
 psycopg2-binary==2.8.5
 whitenoise==3.3.1