Bump django-extensions from 2.2.9 to 3.1.3 in /requirements

Bumps [django-extensions](https://github.com/django-extensions/django-extensions) from 2.2.9 to 3.1.3.
- [Release notes](https://github.com/django-extensions/django-extensions/releases)
- [Changelog](https://github.com/django-extensions/django-extensions/blob/main/CHANGELOG.md)
- [Commits](django-extensions/django-extensions@2.2.9...3.1.3)

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