Bump django from 4.2.18 to 4.2.20 in /requirements

Bumps [django](https://github.com/django/django) from 4.2.18 to 4.2.20.
- [Commits](https://github.com/django/django/compare/4.2.18...4.2.20)

---
updated-dependencies:
- dependency-name: django
  dependency-version: 4.2.20
  dependency-type: direct:production
...

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