Bump gunicorn from 19.6.0 to 22.0.0

Bumps [gunicorn](https://github.com/benoitc/gunicorn) from 19.6.0 to 22.0.0.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](benoitc/gunicorn@19.6.0...22.0.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

requirements-app.txt

@@ -1,6 +1,6 @@
 spacy
 pattern
-gunicorn==19.6.0
+gunicorn==22.0.0
 flask
 sqlalchemy
 pytest