Bump django from 1.11.7 to 2.2.24

Bumps [django](https://github.com/django/django) from 1.11.7 to 2.2.24.
- [Release notes](https://github.com/django/django/releases)
- [Commits](django/django@1.11.7...2.2.24)

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

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

Author: dependabot[bot]

requirements.txt

@@ -1,5 +1,5 @@
 dj-database-url==0.4.2
-Django==1.11.7
+Django==2.2.24
 gunicorn==19.7.1
 psycopg2==2.7.3.1
 whitenoise==3.3.1