chore: prepare release (#2077)

Author: willydouhard

CHANGELOG.md

@@ -4,6 +4,21 @@ All notable changes to Chainlit will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
+## [2.4.400] - 2025-03-29
+
+### Added
+
+- `@cl.on_app_startup` and `@cl.on_app_shutdown`
+- Configuration option for chat history default open state
+- Configuration option for login page background image and filter
+- Most commonly customized ui elements now have specific IDs
+
+### Fixed
+
+- App should no longer flicker on load
+- Attachments icons for microsoft files should now correctly display
+- Pasting should no longer be duplicated
+
 ## [2.4.302] - 2025-03-26
 
 ### Added

backend/chainlit/version.py

@@ -5,4 +5,4 @@
 except metadata.PackageNotFoundError:
     # Case where package metadata is not available, default to a 'non-outdated' version.
     # Ref: config.py::load_settings()
-    __version__ = "2.4.302"
+    __version__ = "2.4.400"

backend/pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "chainlit"
-version = "2.4.302"
+version = "2.4.400"
 keywords = [
     'LLM',
     'Agents',