chore: set Vitest reporter for github actions

[dummdidumm]

test failures show up really bad now, this hopefully fixes it

[pkg-svelte-dev]

Install the latest version of svelte from 403f7c7:

pnpm add https://pkg.svelte.dev/svelte/c/403f7c752ed421023954611bfbfbc12a6d88e699

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/svelte/pr/18722

[changeset-bot]

⚠️ No Changeset found

Latest commit: 403f7c7

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.

This PR includes no changesets

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-svelte-18722-svelte.vercel.app/