Bump django from 2.1 to 2.2.24

Bumps [django](https://github.com/django/django) from 2.1 to 2.2.24.
- [Release notes](https://github.com/django/django/releases)
- [Commits](https://github.com/django/django/compare/2.1...2.2.24)

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

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

requirements.txt

@@ -1,4 +1,4 @@
-Django==2.1
+Django==2.2.24
 django-autocomplete-light==3.3.2
 pytz==2018.5
 simplejson==3.16.0