Add release pipeline

[nojaf]

This is a first attempt to work towards releasing mlflow-go on Pypi. I do have some open questions about this though:

• What version schema do we use? Eventually, I think aligning with mlflow makes sense but for now I would go with 0.X.Y prelease.
• How do we want to trigger a release? Creating a tag via the UI? That trigger the release job?
• What about a changelog? I like something like https://keepachangelog.com/en/1.1.0/ but I'm not sure what mlflow does here.