chore: bump to pnpm 12

[teemingc]

Let's see if there's any advantage to using the Rust-ified pnpm in CI https://pnpm.io/blog/releases/12.0

EDIT: ok seems to shave off 3-8 seconds on Node setup depending on the Node version (24 is faster than 22)

[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from 0e6c710:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/0e6c7101fcab0d346039a6ce3f74da2952ddf533

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16952

[changeset-bot]

⚠️ No Changeset found

Latest commit: 0e6c710

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-16952-svelte.vercel.app/

[Nic-Polumeyv]

Awesome!

Once pnpm/setup#30 (caches the lockfile verification log, which costs 2.6s of the 4.3s install on every job) and pnpm/setup#39 (stops each job from downloading Node again) are released, we should bump pnpm/setup.