Update version in CHANGELOG.md (#36)

Prepare the CHANGELOG for v0.3.0 release.

Author: thunderboltsid

CHANGELOG.md

@@ -5,6 +5,8 @@ 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]
+
+## [0.3.0] - 2022-09-27
 ### Added
 - Added the "environment" package which provides abstraction for retrieving settings like API endpoints, credentials and their sources to evolve independently from clients
 - Add logr based configurable logging for internal.NewClient