build(deps): update gunicorn requirement from ~=20.0 to ~=20.1

Updates the requirements on [gunicorn](https://github.com/benoitc/gunicorn) to permit the latest version.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](https://github.com/benoitc/gunicorn/compare/20.0.0...20.1.0)

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

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

requirements.txt

@@ -7,7 +7,7 @@ feedparser~=6.0.8
 flask~=2.0.2
 flask-caching~=1.10.1
 google-cloud-logging~=2.7.0
-gunicorn~=20.0
+gunicorn~=20.1
 mf2util~=0.5.1
 mox3~=0.28
 requests~=2.26