* Use platform.system for Darwin comparisons
In Python3, `platform.platform()` returns `macOS-10.15.6-x86_64-i386-64bit` instead of `Darwin-10.15.6-x86_64-i386-64bit`.
`platform.system()` returns `Darwin` On py2 and py3.
* Add changlog fragment
* Update changelogs/fragments/945-darwin-timezone-py3.yaml
Co-authored-by: Felix Fontein <felix@fontein.de>
Co-authored-by: Felix Fontein <felix@fontein.de>
Matt Martz