fix: correct yarn detection

[LekoArts]

Hi! 👋
Thanks for the project, it has been of great help for my own project: https://github.com/LekoArts/secco

I've found a small bug in this codepath:

const packageManager =
  packageManagers.find(
    (pm) => pm.name === name && pm.majorVersion === majorVersion,
  ) || packageManagers.find((pm) => pm.name === name);

The comparison of pm.majorVersion === majorVersion will currently be 3.0.0 === 3, so it'll fall back to the first name found. So if you e.g. run the detection in a yarn berry project you won't get back the files array.

In 3b0f0aa I added the assertion of files to the tests, which then were failing. The commit after that fixes it.

I'll leave some inline comments that we could consider for future PRs but I wanted to discuss first.

[LekoArts]

It would probably be a breaking change, but from a usability standpoint this here would be better:

name: "yarn-berry"
majorVersion: ["3", "4"]

Because right now on any new yarn berry project (the current major is 4) this whole detection system won't work. And there is no real differentiation between yarn classic and yarn berry.

So in my own code I need to write this at the moment:

if (pm.name === 'yarn' && (pm.majorVersion === "3" || pm.majorVersion === "4")) {}

Would be cool to be able to write this instead:

if (pm.name === 'yarn-berry') {}

[pi0]

LGTM. thanks.