Bump django-debug-toolbar from 3.1 to 3.1.1

Bumps [django-debug-toolbar](https://github.com/jazzband/django-debug-toolbar) from 3.1 to 3.1.1.
- [Release notes](https://github.com/jazzband/django-debug-toolbar/releases)
- [Changelog](https://github.com/jazzband/django-debug-toolbar/blob/master/docs/changes.rst)
- [Commits](jazzband/django-debug-toolbar@3.1...3.1.1)

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

requirements.txt

@@ -1,6 +1,6 @@
 coverage==5.3
 Django==2.2.16
-django-debug-toolbar==3.1
+django-debug-toolbar==3.1.1
 docutils==0.16
 freezegun==1.0.0
 django-formtools==2.2