Log Message:
py-natsort: updated to 6.1.0

6.1.0:
Added
 - Expose `numeric_regex_chooser` as a public function for ease in making
   key functions
 - Example in the documentation on how to sort numbers with units
 - Automated testing support for macos and Windows

Changed
 - Update CHANGELOG format to style from https://keepachangelog.com/

Fixed
 - Removed dependency on `sudo` in TravisCI configuration
 - Documentation typos