Update django-grappelli to 3.0.4

[pyup-bot]

This PR updates django-grappelli from 2.14.2 to 3.0.4.

Changelog

3.0.4

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* Fixed race condition issue with Grunt.
* Fixed readonly ID field.

3.0.3

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* Fixed utf-8 characters in TinyMCE staticfiles.

3.0.2

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* Fixed changelist actions.

3.0.1

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* First release of Grappelli which is compatible with Django 4.0.

Links

• PyPI: https://pypi.org/project/django-grappelli
• Changelog: https://pyup.io/changelogs/django-grappelli/
• Docs: http://django-grappelli.readthedocs.org

[pyup-bot]

Closing this in favor of #180