Bump version to 2.1, changelog for unreleased @data_layer (#1508)

* Bump version to 2.1.dev0
* Unreleased changelog for 3.0 series, starting with @data_layer.

CHANGELOG.md

@@ -4,6 +4,23 @@ 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/).
 
+## [2.1.dev0] - 2024-11-14
+
+Pre-release: developer preview.
+
+### Added
+- New `@data_layer` decorator for configuring custom data layers declaratively
+- Unit tests for `get_data_layer()` and `@data_layer` functionality
+
+### Changed
+- Data layer configuration system now prioritizes `@data_layer` decorator over environment variables
+- Data layer initialization is now more explicit and testable through the decorator pattern
+- Updated example code in `/cypress/e2e/custom_data_layer` and `/cypress/e2e/data_layer` to use the new decorator
+
+### Developer Experience
+- Improved test infrastructure with new fixtures for data layer mocking
+- Added comprehensive tests for data layer configuration scenarios
+
 ## [1.3.2] - 2024-11-08
 
 ### Security Advisory

backend/pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "chainlit"
-version = "2.0rc0"
+version = "2.1.dev0"
 keywords = [
     'LLM',
     'Agents',