Update changelog regarding horizontal width auto fix (#1192)

Co-authored-by: Dave Pearson <[email protected]>

Author: darrenburns

CHANGELOG.md

@@ -38,6 +38,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Fixed DataTable row not updating after add https://github.com/Textualize/textual/issues/1026
 - Fixed issues with animation. Now objects of different types may be animated.
 - Fixed containers with transparent background not showing borders https://github.com/Textualize/textual/issues/1175
+- Fixed auto-width in horizontal containers https://github.com/Textualize/textual/pull/1155
 
 ## [0.4.0] - 2022-11-08