update changelog

Author: RobinMalfait

CHANGELOG.md

@@ -22,6 +22,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - PostCSS: Ensure that errors in stylesheet dependencies are recoverable ([#17754](https://github.com/tailwindlabs/tailwindcss/pull/17754))
 - Upgrade: Correctly print variants starting with `@` ([#17814](https://github.com/tailwindlabs/tailwindcss/pull/17814))
 - Skip `color-mix(…)` when opacity is `100%` ([#17815](https://github.com/tailwindlabs/tailwindcss/pull/17815))
+- Upgrade: Don't format stylesheets when nothing changed ([#17824](https://github.com/tailwindlabs/tailwindcss/pull/17824))
 
 ## [4.1.4] - 2025-04-14