Bump django from 3.2.20 to 3.2.23 in /backend/requirements

Bumps [django](https://github.com/django/django) from 3.2.20 to 3.2.23.
- [Commits](django/django@3.2.20...3.2.23)

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

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

backend/requirements/dev.txt

@@ -16,7 +16,7 @@ certifi==2023.7.22
     # via requests
 charset-normalizer==2.1.0
     # via requests
-django==3.2.20
+django==3.2.23
     # via
     #   -r requirements.in/base.txt
     #   django-cors-headers

backend/requirements/prod.txt

@@ -8,7 +8,7 @@ asgiref==3.7.2
     # via django
 audioread==3.0.0
     # via -r requirements.in/base.txt
-django==3.2.20
+django==3.2.23
     # via
     #   -r requirements.in/base.txt
     #   django-cors-headers