Update CHANGELOG.md

Author: schloerke

CHANGELOG.md

@@ -5,7 +5,7 @@ All notable changes to Shiny for Python will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [UNRELEASED]
+## [1.4.0] - 2025-04-08
 
 ## New features
 
@@ -17,8 +17,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * Both `ui.Chat()` and `ui.MarkdownStream()` now support the inclusion of Shiny UI elements inside of messages. This allows for gathering input from the user (e.g., `ui.input_select()`), displaying of rich output (e.g., `render.DataGrid()`), and more. (#1868)
 
-* Added a new `.message_stream_context()` method to `ui.Chat()`. This context manager is a useful alternative to `.append_message_stream()` when you want to: (1) Nest a stream within another and/or
-(2) Overwrite/replace streaming content. (#1906)
+* Added a new `.message_stream_context()` method to `ui.Chat()`. This context manager is a useful alternative to `.append_message_stream()` when you want to: (1) Nest a stream within another and/or (2) Overwrite/replace streaming content. (#1906)
 
 ### Changes