Bump django from 1.11.6 to 2.2.24

Bumps [django](https://github.com/django/django) from 1.11.6 to 2.2.24.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@1.11.6...2.2.24)

---
updated-dependencies:
- dependency-name: django
  dependency-type: direct:production
...

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

requirements.txt

@@ -1,5 +1,5 @@
 dj-database-url==0.4.2
-Django==1.11.29
+Django==2.2.24
 django-widget-tweaks==1.4.1
 Markdown==2.6.9
 python-decouple==3.1