chore(deps): bump gunicorn from 20.1.0 to 21.2.0 (#18)

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

requirements.txt

@@ -1,5 +1,5 @@
 Django==4.1.13
-gunicorn==20.1.0
+gunicorn==21.2.0
 mysqlclient==2.1.1
 oauthlib==3.2.2
 pytz==2023.3.post1