Bump django-filter from 2.4.0 to 21.1

Bumps [django-filter](https://github.com/carltongibson/django-filter) from 2.4.0 to 21.1.
- [Release notes](https://github.com/carltongibson/django-filter/releases)
- [Changelog](https://github.com/carltongibson/django-filter/blob/main/CHANGES.rst)
- [Commits](carltongibson/django-filter@2.4.0...21.1)

---
updated-dependencies:
- dependency-name: django-filter
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

requirements/base.txt

@@ -1,6 +1,6 @@
 # Bleeding edge Django
 
-django==2.2.25
+django==2.2.27
 
 # Configuration
 django-environ==0.4.5
@@ -19,7 +19,7 @@ social-auth-core==3.3.3
 djangorestframework==3.11.2
 djangorestframework-gis==0.17
 djangorestframework-csv==2.1.1
-django-filter==2.4.0
+django-filter==21.1
 django-cors-headers==3.7.0
 drf-yasg==1.20.0