update changelog

Author: Conduitry

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 * Fix misaligned line numbers in source maps ([#3906](https://github.com/sveltejs/svelte/issues/3906))
 * Fix reactivity with imported values that are then mutated ([#4555](https://github.com/sveltejs/svelte/issues/4555))
+* Display a11y warning for `href="javascript:..."` ([#4733](https://github.com/sveltejs/svelte/pull/4733))
 
 ## 3.21.0