Update django-extensions to 3.0.0

[pyup-bot]

This PR updates django-extensions from 2.2.9 to 3.0.0.

Changelog

3.0.0

-----

This is the first Django Extensions release which only targets Django 2.2 and above.
It drops official support for Python 2.7.


Changes:
- Removal of Python 2 support
- Removal of deprecated keyczar encrypted fields EncryptedTextField and EncryptedCharField
- Removal of deprecated passwd command
- Removal of truncate_letters filter
- Change: TimeStampedModel; Removed default ordering on abstract model
- New: DjangoExtensionsConfig AppConfig
- New: shell_plus, JupyterLab support
- New: list_signals, List all signals by model and signal type
- Improvement: shell_plus, use -- to directly pass additional arguments to Jupyter
- Improvement: shell_plus, improvements to MySQL support
- Improvement: jobs, use logging to record errors
- Improvement: syncdata, added --remove-before flag
- Improvement: graph_models, add field and model to template context
- Fix: syncdata, fix non existent field in fixture data
- Fix: pipchecker, compatibility with pip 20.1

Links

• PyPI: https://pypi.org/project/django-extensions
• Changelog: https://pyup.io/changelogs/django-extensions/
• Repo: http://github.com/django-extensions/django-extensions

[coveralls]

Coverage remained the same at 96.926% when pulling 9a8b8f4 on pyup-update-django-extensions-2.2.9-to-3.0.0 into ac886a3 on master.

[pyup-bot]

Closing this in favor of #348