Match all juliaup channel names

[IanButterworth]

release not being supported here is confusing. etc.

[ViralBShah]

@DilumAluthge Another v3 candidate.

[DilumAluthge]

If the desired channel name currently errors in this action, then I think we can add it in a non-breaking release, because we'd be going from error ---> non-error.

If there are channels that currently work in this action, and we want to change the behavior, then that would be breaking.

[DilumAluthge]

I think we can achieve the goal here (add support to setup-julia for all the same channel names that Juliaup supports) without needing a breaking change of setup-julia.