chore: update index.spec.js assertions

[teemingc]

follow up to b7b9025 to get the unit tests passing

[pkg-svelte-dev]

Install the latest version of @sveltejs/kit from f5015fb:

pnpm add https://pkg.svelte.dev/@sveltejs/kit/c/f5015fb95440376d99ced6a8a043be8a90842511

Open in pkg.svelte.dev: https://pkg.svelte.dev/repos/kit/pr/16395

[changeset-bot]

⚠️ No Changeset found

Latest commit: f5015fb

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[Rich-Harris]

my bad, I thought I was pushing to #16374 😬