chore(deps): bump gunicorn from 22.0.0 to 23.0.0 in /backend

Bumps [gunicorn](https://github.com/benoitc/gunicorn) from 22.0.0 to 23.0.0.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](benoitc/gunicorn@22.0.0...23.0.0)

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

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

Author: dependabot[bot]

backend/requirements.txt

@@ -13,7 +13,7 @@ flake8-commas==2.0.0
 flake8-mypy==17.8.0
 gevent==23.9.1
 greenlet==0.4.14
-gunicorn==22.0.0
+gunicorn==23.0.0
 idna==3.7
 ipython==8.10.0
 ipython-genutils==0.2.0