Update django-widget-tweaks to 1.4.8

[pyup-bot]

This PR updates django-widget-tweaks from 1.4.5 to 1.4.8.

Changelog

1.4.8

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* Fix Release version

1.4.7

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* Fix Travis deployment to Jazzband site

1.4.6

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* Feature remove attribute from field
* Added documentation for remove_attr feature
* Reformat code with black for PEP8 compatibility 
* More consistent tox configuration
* adding a new templatetag, unittest and documentation
* Deprecate Python 2.7 support
* Use automatic formatting for all files

Links

• PyPI: https://pypi.org/project/django-widget-tweaks
• Changelog: https://pyup.io/changelogs/django-widget-tweaks/
• Repo: https://github.com/jazzband/django-widget-tweaks