Add option to use latest pnpm

[ai]

I want an option or version value to use latest pnpm version.

    - uses: pnpm/action-setup@v2
      with:
        version: latest

Motivation

I have many open source projects and it is hard to update pnpm in all of them.

Side Effect

I understand that some projects need repeatability for CI. So latest will not fit their use case. But my projects are small and for my case repeatability is not so important compare to maintainability.

We can promote exact version in docs and keep latest only for people who need it.

[KSXGitHub]

Shouldn't it already be possible? Can you check it again?

[ai]

Yeap. It works :D

https://github.com/browserslist/browserslist/runs/4547570018

Should we add a small note to version option?

[KSXGitHub]

I'm busy right now, so a pull request is welcomed. Also, it should support semver, can you please check it as well while we are at it?

[ai]

Sure. I will check 6 and 6.4 options and then will send PR.

Thanks for quick replies.