Bump svelte from 3.55.0 to 4.2.15 in /templates/svelte-basic

Bumps [svelte](https://github.com/sveltejs/svelte/tree/HEAD/packages/svelte) from 3.55.0 to 4.2.15.
- [Release notes](https://github.com/sveltejs/svelte/releases)
- [Changelog](https://github.com/sveltejs/svelte/blob/svelte@4.2.15/packages/svelte/CHANGELOG.md)
- [Commits](https://github.com/sveltejs/svelte/commits/svelte@4.2.15/packages/svelte)

---
updated-dependencies:
- dependency-name: svelte
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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