Update python-magic to 0.4.27

[pyup-bot]

This PR updates python-magic from 0.4.25 to 0.4.27.

Changelog

0.4.27

- remove spurious pyproject.toml that breaks source builds

0.4.26

- Use tox for all multi-version testing
- Fix use of pytest, use it via tox

Links

• PyPI: https://pypi.org/project/python-magic
• Changelog: https://pyup.io/changelogs/python-magic/
• Repo: http://github.com/ahupp/python-magic