setup-cue: support non-release versions

[myitcv]

Is your feature request related to a problem? Please describe.

The current README for setup-cue says the following:

Use this action in your GitHub Actions workflow to install a specific version of CUE on your runner. The input version is a version string like v0.6.0, or v0.6.0-beta.1. You can also use the version query latest (default) to use the latest release of cue. Releases and pre-releases of cue are listed here.

The last sentence being key. i.e. only official releases are supported as target versions.

As such, it's impossible to track master (the tip of CUE) or a specific pseudo-version.

Describe the solution you'd like

Support within setup-cue to specify the special version @master or a specific pseudo-version. Using such a target Go version would create the pre-requisite that Go be available in the environment, which would therefore necessitate the called to have run setup-go or similar before setup-cue. This seems like a reasonable requirement.

Describe alternatives you've considered

Nothing that scales particularly well. Creating a release for everyone pseudo-version feels version expensive.

Additional context

n/a