Update bump2version to 1.0.0

[pyup-bot]

This PR updates bump2version from 0.5.11 to 1.0.0.

Changelog

1.0.0

- Fix the spurious newline that bump2version adds when writing to bumpversion.cfg, thanks kyluca 58
- Add Python3.8 support, thanks florisla 
- Drop Python2 support, thanks hugovk
- Allow additional arguments to the commit call, thanks lubomir
- Various documentation improvements, thanks lubomir florisla padamstx glotis
- Housekeeping, move changelog into own file

Links

• PyPI: https://pypi.org/project/bump2version
• Changelog: https://pyup.io/changelogs/bump2version/
• Repo: https://github.com/c4urself/bump2version