Release to pypi

[CloudNiner]

Release to pypi via github actions CI when a new tag is published.

The requisite env variables should already be added to this repo's secrets list.

Use azavea/pystac-io#9 as a guide

Include CHANGELOG and RELEASE instructions

[CloudNiner]

In the meantime, this can be pip installed from github with minimal hassle by adding the following to your pip requirements.txt:

geopandas==0.8.1
git+https://github.com/azavea/stacframes.git@dd7959d1a9fee7227624aa185f797402209b0ad0

Substitute the hash in the git url with whatever the HEAD of master is at the time: https://github.com/azavea/stacframes/commits/master