Add explicit `packageManager` field to `package.json`

[aryaemami59]

This PR:

• [X] Adds explicit packageManager field to package.json.

[ai]

I have 50+ open source projects, it will be very hard for me keep up to date to version of pnpm in package.json manually in every project.

Do you have any reason why this key is important to spend more time on maintenance?

[aryaemami59]

Mostly because corepack needs it, but there are some other reasons:

• Allow contributors to have the same version of pnpm.
• The pnpm/action-setup reads the packageManager field so basically all we're doing is moving the version specification from the test.yml file to package.json.
• If you don't have it, corepack adds it automatically so there can be a version mismatch.
• Bumping the version is as simple as running corepack use pnpm@*, which is easier to do and can be automated, as opposed to manually editing the test.yml file.

I understand if you're not on board with this, and if not, just say so and I'll go ahead and close the PR, but if you're okay with it, I can help put up PRs for the rest of your libraries (yes all 50+).

[ai]

I really afraid of locking the exact version of pnpm.

What if there is old project with 9.1.1 and new developer come with 9.2? Will it require too many versions of pnpm on developers machine in corepack?

[aryaemami59]

In that case, they will already have version 9.1.1 on their machine, since corepack caches the old versions on the global registry, and will not remove them unless they call corepack cache clear manually.

[ai]

I decided to not use it right now. It is better to use the latest pnpm.