Add H3

[ajfriend]

This is very cool. Would you consider adding H3 cell geographies?

https://uber.github.io/h3-py/
https://h3geo.org/

You could do multiple resolutions, but something around resolution 9 could be useful.

[dfsnow]

@ajfriend I'd actually love to do this for a V2 of OpenTimes, but I'm mostly focused on my new role at the moment. If I get free time toward the end of the year, I'll probably try to transition OpenTimes fully to H3 and expand coverage.

[ajfriend]

No worries! I'll look forward to it. Let me know if there's anything I can help with, especially around the H3 stuff.