Upgrade some dependencies when we want to drop Node 14

[n-peugnet]

• [x] https://rollupjs.org/migration/
• [x] https://github.com/kaisermann/svelte-i18n/blob/main/CHANGELOG.md#400-2023-10-16
• [x] https://svelte.dev/docs/v4-migration-guide
• [ ] https://eslint.org/docs/latest/use/migrate-to-9.0.0 later
• [x] https://github.com/sveltejs/svelte-preprocess/blob/main/docs/migration-guide.md#from-v5-to-v6