Update changelog

Author: adamwathan

CHANGELOG.md

@@ -965,7 +965,8 @@ No release notes
 
 - Everything!
 
-[unreleased]: https://github.com/tailwindlabs/tailwindcss/compare/v1.8.13...HEAD
+[unreleased]: https://github.com/tailwindlabs/tailwindcss/compare/v1.9.0...HEAD
+[1.9.0]: https://github.com/tailwindlabs/tailwindcss/compare/v1.8.13...v1.9.0
 [1.8.13]: https://github.com/tailwindlabs/tailwindcss/compare/v1.8.12...v1.8.13
 [1.8.12]: https://github.com/tailwindlabs/tailwindcss/compare/v1.8.11...v1.8.12
 [1.8.11]: https://github.com/tailwindlabs/tailwindcss/compare/v1.8.10...v1.8.11