build(deps): bump gunicorn from 20.1.0 to 21.2.0 (#55)

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

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

requirements.txt

@@ -2,7 +2,7 @@ Django==4.2.5
 django-phonenumber-field==7.1.0
 djangorestframework==3.14.0
 
-gunicorn==20.1.0
+gunicorn==21.2.0
 
 phonenumbers==8.13.20
 psycopg2-binary==2.9.7