Bump gunicorn from 20.1.0 to 22.0.0 in /flask

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>

Author: dependabot[bot]

flask/requirements.txt

@@ -1,6 +1,6 @@
 flask==2.3.2
 Werkzeug>=2.2,<3.0 # 3.0 removes deprecated stuff flask 2.3.2 uses
-gunicorn==20.1.0
+gunicorn==22.0.0
 Flask-SQLAlchemy==3.0.2
 Flask-Migrate==3.1.0
 GitHub-Flask==3.2.0