Bump djangorestframework from 3.14.0 to 3.15.0 in /api_server

Bumps [djangorestframework](https://github.com/encode/django-rest-framework) from 3.14.0 to 3.15.0.
- [Release notes](https://github.com/encode/django-rest-framework/releases)
- [Commits](encode/django-rest-framework@3.14.0...3.15.0)

---
updated-dependencies:
- dependency-name: djangorestframework
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

api_server/requirements.txt

@@ -1,5 +1,5 @@
 Django==5.0.2
-djangorestframework==3.14.0
+djangorestframework==3.15.0
 psycopg2-binary==2.9.9
 tzdata==2024.1
 djangorestframework-simplejwt==5.3.1