chore(deps): bump gunicorn in /example/flask-gunicorn

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>

example/flask-gunicorn/requirements.txt

@@ -4,4 +4,4 @@ flask_sqlalchemy==2.5.1
 itsdangerous==2.1.2
 opentelemetry-instrumentation-flask==0.38b0
 opentelemetry-instrumentation-sqlalchemy==0.38b0
-gunicorn==20.0.4
+gunicorn==22.0.0