update changelog (#243)

Author: nsidnev

CHANGELOG.md

@@ -5,7 +5,11 @@ All notable changes to this project 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).
 
-## [0.9.0] - 2025-02-26
+## [Unreleased]
+
+[Compare with 0.9.0](https://github.com/geldata/gel-elixir/compare/v0.9.0...HEAD)
+
+## [0.9.0] - 2025-03-07
 
 [Compare with 0.8.0](https://github.com/geldata/gel-elixir/compare/v0.8.0...v0.9.0)