This is a Unity Package Manager compatible version of Esoteric Software's Spine Unity runtime based on a .unitypackage obtained from this page.

In your manifest.json, add this line to pull into your project.

    "com.esotericsoftware.spine": "git://github.com/5argon/spine-unity-upm.git",

To update, delete the lock section appeared at bottom of the manifest.json.