Update gitpython to 3.0.4

[pyup-bot]

This PR updates gitpython from 3.0.2 to 3.0.4.

Changelog

3.0.4

=============================================

see the following for details:
https://github.com/gitpython-developers/gitpython/milestone/31?closed=1

3.0.3

=============================================

see the following for (most) details:
https://github.com/gitpython-developers/gitpython/milestone/30?closed=1

Links

• PyPI: https://pypi.org/project/gitpython
• Changelog: https://pyup.io/changelogs/gitpython/
• Repo: https://github.com/gitpython-developers/GitPython
• Docs: https://pythonhosted.org/GitPython/

[pyup-bot]

Closing this in favor of #110