chore(deps): update djangorestframework requirement in /api

Updates the requirements on [djangorestframework](https://github.com/encode/django-rest-framework) to permit the latest version.
- [Release notes](https://github.com/encode/django-rest-framework/releases)
- [Commits](encode/django-rest-framework@3.14.0...3.15.1)

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

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

api/requirements.txt

@@ -4,7 +4,7 @@ coverage~=7.4.4
 cryptography~=42.0.5
 Django~=5.0.4
 django-cors-headers~=4.3.1
-djangorestframework~=3.14.0
+djangorestframework~=3.15.1
 django-celery-email~=3.0.0
 django-netfields~=1.3.2
 django-pgtrigger~=4.11.1