Bump gunicorn from 20.1.0 to 21.2.0

Bumps [gunicorn](https://github.com/benoitc/gunicorn) from 20.1.0 to 21.2.0.
- [Release notes](https://github.com/benoitc/gunicorn/releases)
- [Commits](benoitc/gunicorn@20.1.0...21.2.0)

---
updated-dependencies:
- dependency-name: gunicorn
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

pyproject.toml

@@ -14,7 +14,7 @@ django-plausible-proxy = "~0.5"
 django-storages = "^1.13.2"
 django-widget-tweaks = "^1.4.8"
 factory-boy = "^3.3.0"
-gunicorn = "^20.1.0"
+gunicorn = "^21.2.0"
 heroicons = {extras = ["django"], version = "^1.4.0"}
 psycopg2 = "^2.9.6"
 python = "^3.11"