update changelog

Author: RobinMalfait

CHANGELOG.md

@@ -22,6 +22,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Prevent `@source` patterns from scanning unrelated sibling files and folders ([#20263](https://github.com/tailwindlabs/tailwindcss/pull/20263))
 - Extract class candidates adjacent to Template Toolkit delimiters like `%]…[%` in `.tt`, `.tt2`, and `.tx` files ([#20269](https://github.com/tailwindlabs/tailwindcss/pull/20269))
 - Extract class candidates from conditional Maud syntax like `p.text-black[condition]` ([#20269](https://github.com/tailwindlabs/tailwindcss/pull/20269))
+- Prevent `@position-try` rules from triggering unknown at-rule warnings when optimizing CSS ([#20277](https://github.com/tailwindlabs/tailwindcss/pull/20277))
 
 ## [4.3.1] - 2026-06-12