We occasionally create a git tag that matches an editor version:
Tags
However, 3.x versions of the editor will work with the runtimes found in the 3.x git branch. Eg, all 3.6.xx editor versions work with any commit in the 3.6 branch. There should not be any reason to use older commits though, the latest in the 3.6 branch has the latest fixes and is compatible with all 3.6.xx editor versions. There also should not be any reason to use older 3.6 editor versions, the latest 3.6 editor version has the latest fixes. However, we still recommend freezing your editor and runtime versions and always testing first before moving your teams to the latest versions. Also, never upgrade Spine (or any other dependency) right before a release!