deps: bump django from 4.2.20 to 4.2.21

Bumps [django](https://github.com/django/django) from 4.2.20 to 4.2.21.
- [Commits](django/django@4.2.20...4.2.21)

---
updated-dependencies:
- dependency-name: django
  dependency-version: 4.2.21
  dependency-type: direct:production
...

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

Author: dependabot[bot]

requirements.txt

@@ -23,7 +23,7 @@ charset-normalizer==3.3.2
     # via requests
 deprecation==2.1.0
     # via django-helusers
-django==4.2.20
+django==4.2.21
     # via
     #   -r requirements.in
     #   django-cors-headers