chore: remove pnpm devDependency

[dominikg]

Description

found that during debugging an issue in vite-ecosystem-ci and havn't seen any usage of it.
Having it as a local devDependency causes it to be used over global pnpm after the global was used for the initial install.
This can cause mismatches.

If we want to enforce a certain pnpm version, using engines.pnpm alongside the already set packageManager field would be a better option imho.

Additional context

---

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

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[sapphi-red]

My understanding is that this exists to lock the version of pnpm used here.

vite/netlify.toml

Line 6 in c56b954

command = "npx pnpm i --store=node_modules/.pnpm-store --frozen-lockfile && npm run ci-docs"

So I think we can remove this when we can revert #11477. (#11759)

[dominikg]

pinning pnpm that way comes with the drawbacks mentioned above and seeing that the current value is ^7.25.0 which isn't really pinning, i think it would be better to use npx pnpm@version ... in that script if we have that need again in the future

[sapphi-red]

Ah, that makes sense.