chore: bump svelte2tsx

[teemingc]

Bumps svelte-package's deps to support TypeScript 6. Also updates the test fixtures to match TypeScript 6's output. Not sure if we want to keep both TypeScript 5 and 6 expected output and add a matrix to CI 😓

This is the last step before we make TypeScript 6 the minimum in the version-3 branch

EDIT: requires merging sveltejs/svelte-preprocess#680 first, then releasing a new version and bumping svelte-preprocess to get the tests passing.

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[teemingc]

Just changing these so that it's easier to maintain the TypeScript we use purely for development