update changelog

Author: Conduitry

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## Unreleased
 
 * Fix setting reactive dependencies which don't appear in the template to `undefined` ([#5538](https://github.com/sveltejs/svelte/issues/5538))
+* Support preprocessor sourcemaps during compilation ([#5584](https://github.com/sveltejs/svelte/pull/5584))
 * Fix ordering of elements when using `{#if}` inside `{#key}` ([#5680](https://github.com/sveltejs/svelte/issues/5680))
 * Add `hasContext` lifecycle function ([#5690](https://github.com/sveltejs/svelte/pull/5690))
 * Fix missing `walk` types in `svelte/compiler` ([#5696](https://github.com/sveltejs/svelte/pull/5696))