Provide configurable time zone for dates

[rootwork]

Is your feature request related to a problem? Please describe.

I know this is relatively minor, but because github-changelog-generator uses UTC and my team is many hours west of UTC, releases late in the day get labeled with the next day's date. It's not a huge deal, but we have to remember "yeah that was the release that actually happened the day before."

Describe the solution you'd like

A configurable time zone setting (or UTC offset, whatever's easier).

Describe alternatives you've considered

Living with it ¯\_(ツ)_/¯

Additional context
none