Bump gunicorn from 23.0.0 to 24.1.1 in /backend

Bumps [gunicorn](https://github.com/benoitc/gunicorn) from 23.0.0 to 24.1.1.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](benoitc/gunicorn@23.0.0...24.1.1)

---
updated-dependencies:
- dependency-name: gunicorn
  dependency-version: 24.1.1
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

backend/poetry.lock

@@ -151,7 +151,7 @@ django-cors-headers = "4.*"
 dataclasses-json = "0.*"
 django-guardian = "2.*"
 pillow = "11.*"
-gunicorn = "23.*"
+gunicorn = "25.*"
 django-admin-autocomplete-filter = "0.*"
 psycopg = { extras = ["c"], version = "*" }