update changelog

Author: RobinMalfait

CHANGELOG.md

@@ -33,6 +33,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Ensure transitions between `inset-shadow-none` and other inset shadows work correctly ([#20208](https://github.com/tailwindlabs/tailwindcss/pull/20208))
 - Ensure explicitly referenced `@source` directories are scanned even when ignored by git ([#20214](https://github.com/tailwindlabs/tailwindcss/pull/20214))
 - Ensure `@source` globs ending in `**/*` preserve dynamic path segments to avoid scanning too many files ([#20217](https://github.com/tailwindlabs/tailwindcss/pull/20217))
+- Canonicalization: don't fold `calc(…)` divisions when the result would require high precision (e.g. `w-[calc(100%/3.5)]` → `w-[calc(100%/3.5)]`, not `w-[28.571428571428573%]`) ([#20221](https://github.com/tailwindlabs/tailwindcss/pull/20221))
 
 ### Changed