New runtime release? Are you talking about 3.2?
This beta spine-csharp 3.2 unitypackage has been out for a few weeks now.
Just import it in your existing Unity project.
It's not beta because it's broken though, as far as I and users have been able to tell, it's ready for production.
And if it's not, we'll fix it and update the beta.
It's only beta because Nate hasn't had the time to check and sign off on it and he's neck-deep in the 3.3 editor update.
[EDIT] The link and file has been updated. The previous beta had a problem.