Moving discussions to GitHub Discussions

[sherma...@gmail.com]

Hello!

After discussion with the team, we've decided to begin to move discussions from pyart google groups to the Py-ART's discussion found on GitHub https://github.com/ARM-DOE/pyart/discussions

This allows us to keep everything centralized as well as mark and group different discussions and much more.

Thanks for your time,

Cheers, The Py-ART Dev Team