[chore] update changelog (#7602)

Author: baseballyama

CHANGELOG.md

@@ -3,7 +3,7 @@
 ## Unreleased
 
 * Faster SSR ([#5701](https://github.com/sveltejs/svelte/pull/5701))
-* Fix `class:` directive updates with `<svelte:element>` ([#7521](https://github.com/sveltejs/svelte/issues/7521))
+* Fix `class:` directive updates with `<svelte:element>` ([#7521](https://github.com/sveltejs/svelte/issues/7521), [#7571](https://github.com/sveltejs/svelte/issues/7571))
 
 ## 3.48.0