update changelog for 0.3.0 (#86)

Author: nsidnev

CHANGELOG.md

@@ -5,9 +5,13 @@ 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).
 
-## [0.3.0] - Unreleased
+## Unreleased
 
-[Compare with 0.2.1](https://github.com/nsidnev/edgedb-elixir/compare/v0.2.1...HEAD)
+[Compare with 0.3.0](https://github.com/nsidnev/edgedb-elixir/compare/v0.3.0...HEAD)
+
+## [0.3.0] - 2022-05-29
+
+[Compare with 0.2.1](https://github.com/nsidnev/edgedb-elixir/compare/v0.2.1...v0.3.0)
 
 ### Added