Bump django-filter from 1.1.0 to 2.4.0

Bumps [django-filter](https://github.com/carltongibson/django-filter) from 1.1.0 to 2.4.0.
- [Release notes](https://github.com/carltongibson/django-filter/releases)
- [Changelog](https://github.com/carltongibson/django-filter/blob/main/CHANGES.rst)
- [Commits](carltongibson/django-filter@1.1.0...2.4.0)

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

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

Author: dependabot[bot]

requirements.txt

@@ -7,7 +7,7 @@ django-jinja==2.4.1
 django-jinja-bootstrap-form==4.0.3
 djangorestframework==3.5.3
 django-rest-swagger==2.1.1
-django-filter==1.1.0 # Needs updating with Django
+django-filter==2.4.0 # Needs updating with Django
 fabric3==1.13.1.post1
 funcy>=1.10,<2.0
 handy==0.7