Add latest-changes GH action

[pydanny]

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

Determining changelog data is messy. It would be good to have something as sweet as this: https://github.com/tiangolo/latest-changes

Describe the solution you'd like

Implement https://github.com/tiangolo/latest-changes for this project

Describe alternatives you've considered

Our current system is a lot of make work with inelegant steps.