Am I correct in thinking that the name Utility is deprecated and the lib is now SPMUtility
Utility no longer exists.
What is the latest release of this lib?
There is no tagged semantic version in the official repository compatible with Swift 5. That is not because there cannot or should not be, but merely because no one did it. You can read the details over in this thread.
The source works fine, so I forked it and tagged a Version 0.0.50000 to correspond with Swift 5.0.0. (It works with Swift 5.0.1 too.) As long as the package manager remains open source, I am committed to tagging any future releases the main repository neglects in the same way.
There is also no documentation hosted anywhere. You can use a tool of mine called Workspace to scan its API locally:
(Edit: You may have to first add a dummy configuration specifying some options like the localization. If it needs you to specify something, it will tell you.)
I also have a wrapper around the package manager, SDGSwift that makes many common tasks much easier. You can use the wrapper as an example of how to use the SwiftPM package, or if you find it helpful, you can even link against the wrapper itself.
How can I actually find [the lastest version] out in the future?
It is not posted anywhere, and GitHub’s list is cluttered with other tags. If you query the tag list with Git, the semantic versions sort nicely into a group together:
$ git ls-remote --tags https://github.com/apple/swift-package-manager