Bump gunicorn from 21.2.0 to 22.0.0

Bumps [gunicorn](https://github.com/benoitc/gunicorn) from 21.2.0 to 22.0.0.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](benoitc/gunicorn@21.2.0...22.0.0)

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

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

Author: dependabot[bot]

Pipfile

@@ -5,7 +5,7 @@ name = "pypi"
 
 [packages]
 flask-migrate = "~=4.0"
-gunicorn = "~=21.2"
+gunicorn = "~=22.0"
 pymysql = "~=1.1"
 slackclient = "~=2.9"