⬆️ Bump gunicorn from 20.1.0 to 22.0.0 in /web_app

Bumps [gunicorn](https://github.com/benoitc/gunicorn) from 20.1.0 to 22.0.0.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](benoitc/gunicorn@20.1.0...22.0.0)

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

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

web_app/requirements.txt

@@ -1,5 +1,5 @@
 Flask==2.3.2
-gunicorn==20.1.0
+gunicorn==22.0.0
 requests==2.31.0
 python-dotenv==1.0.0
 pyjwt==2.7.0