⬆️ Bump gunicorn from 21.2.0 to 22.0.0 in /docker-images (#209)

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
...

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docker-images/requirements.txt

@@ -1,2 +1,2 @@
 uvicorn[standard]==0.21.0
-gunicorn==21.2.0
+gunicorn==22.0.0