feat: support bun and pnpm, update handling for detecting yarn and npm

[michaeljaltamirano]

Sibling to open-turo/actions-node#173. From that PR:

The actions-node GHA is relatively brittle, expecting yarn as the package manager for repos that rely on it, though there is fallback logic to npm if no yarn artifacts are detected. This PR seeks to make the GHA compatible with two other tools: bun and pnpm. (deno was excluded to try not to add too much at once.) This will allow repos that rely on this GHA to use whichever tool best suits the needs for that given repo, without the restriction on yarn (classic) and npm.

[tagoro9]

I wonder if these need to be breaking changes, since not a lot is changing beyond the addition of bun and pnpm? Or if there are breaking changes, I would document them better. I think making these not breaking should be ok too

[tagoro9]

Add more details here on what is changing in the behavior? As a consumer of this lib, what would I have to change?

[github-actions]

Release notes preview

Below is a preview of the release notes if your PR gets merged.

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3.1.0 (2026-01-13)

Features

• support bun and pnpm, update handling for detecting yarn and npm (dd58457)