Update appdirs to 1.4.3

[pyup-bot]

This PR updates appdirs from 1.4.0 to 1.4.3.

Changelog

1.4.3

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- [PR 76] Python 3.6 invalid escape sequence deprecation fixes
- Fix for Python 3.6 support

1.4.2

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- [PR 84] Allow installing without setuptools
- [PR 86] Fix string delimiters in setup.py description
- Add Python 3.6 support

1.4.1

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- [issue 38] Fix _winreg import on Windows Py3
- [issue 55] Make appname optional

Links

• PyPI: https://pypi.org/project/appdirs
• Changelog: https://pyup.io/changelogs/appdirs/
• Repo: http://github.com/ActiveState/appdirs