Update changelog

Author: chipshort

CHANGELOG.md

@@ -4,7 +4,7 @@ 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]
+## [2.0.0-beta.0] - 2023-12-21
 
 ### Added
 
@@ -720,7 +720,9 @@ and this project adheres to
 The CHANGELOG for versions before 1.0.0 was moved to
 [CHANGELOG-pre1.0.0.md](./CHANGELOG-pre1.0.0.md).
 
-[unreleased]: https://github.com/CosmWasm/cosmwasm/compare/v1.5.0...HEAD
+[unreleased]: https://github.com/CosmWasm/cosmwasm/compare/v2.0.0-beta.0...HEAD
+[2.0.0-beta.0]:
+  https://github.com/CosmWasm/cosmwasm/compare/v1.5.0...v2.0.0-beta.0
 [1.5.0]: https://github.com/CosmWasm/cosmwasm/compare/v1.4.1...v1.5.0
 [1.4.1]: https://github.com/CosmWasm/cosmwasm/compare/v1.4.0...v1.4.1
 [1.4.0]: https://github.com/CosmWasm/cosmwasm/compare/v1.3.3...v1.4.0