build(deps): bump gunicorn from 20.0.4 to 22.0.0

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>

requirements.txt

@@ -6,7 +6,7 @@ requests==2.20.0
 SQLAlchemy==1.3.0
 tzlocal==1.2
 WebTest==3.0.0
-gunicorn==20.0.4
+gunicorn==22.0.0
 python-statsd==2.0.0
 mock==2.0.0
 pytest==6.2.4