Allow specifying 'latest' as dotnet-version

[CamJN]

Description:
A workflow with the following would install the latest major version of dotnet.

    - name: Setup .NET
      uses: actions/setup-dotnet@v4
      with:
        dotnet-version: latest

Justification:
It would be nice to be able to just stick latest in the dotnet-version field and not have to update the tag when a new major version comes out. This is available in the node and ruby setup actions and is quite nice.

Are you willing to submit a PR?
Unlikely.

[aparnajyothi-y]

Hello @CamJN,
Thank you for creating this issue, we will investigate it and come back to you as soon as we have some feedback.

[kevinoid]

I'd also appreciate this feature. For reference, it is currently possible to install the latest LTS version with:

    - name: Setup .NET
      uses: actions/setup-dotnet@v4
      with:
        dotnet-version: x

Unfortunately, this always installs a version from the LTS channel due to

setup-dotnet/src/installer.ts

Lines 77 to 78 in 3e891b0

	// If "dotnet-version" is specified as *, x or X resolve latest version of .NET explicitly from LTS channel. The version argument will default to "latest" by install-dotnet script.
	this.resolvedArgument.value = 'LTS';

[vRune4]

I'm utterly confused.

AFAICT the docs state that the latest SDK should be able to build projects that target older versions.

So why would I ever want to lock down the SDK version? Isn't the 80% use case that you'd want to build using the latest project and not have to mess around with strange global.json files?

I have a reusable workflow shared by several projects. These projects will gradually move towards whatever is the latest .net version. They currently do not have a global.json file. I see dependabot can be used to update global.json. (again: why would I want this? Just use the latest SDK already!)