Bump gunicorn in /samples/web-app-cosmosdb-nosql-api/python/src

Bumps [gunicorn](https://github.com/benoitc/gunicorn) from 20.1.0 to 22.0.0.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](benoitc/gunicorn@20.1.0...22.0.0)

---
updated-dependencies:
- dependency-name: gunicorn
  dependency-version: 22.0.0
  dependency-type: direct:production
...

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Author: dependabot[bot]

samples/web-app-cosmosdb-nosql-api/python/src/requirements.txt

@@ -1,6 +1,6 @@
 Flask==3.1.0
 azure-mgmt-cosmosdb==9.8.0
 azure-cosmos==4.7.0
-gunicorn==20.1.0
+gunicorn==22.0.0
 python-dotenv==1.1.1
 setuptools==79.0.1