Bump gunicorn from 20.0.4 to 22.0.0 in /tekton/webhook

Bumps [gunicorn](https://github.com/benoitc/gunicorn) from 20.0.4 to 22.0.0.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](benoitc/gunicorn@20.0.4...22.0.0)

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

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

tekton/webhook/requirements.txt

@@ -1,6 +1,6 @@
 Click==7.0
 Flask==2.3.2
-gunicorn==20.0.4
+gunicorn==22.0.0
 itsdangerous==1.1.0
 Jinja2==2.11.3
 MarkupSafe==1.1.1