Update changelog for release 0.0.3

Author: ilario-pierbattista

CHANGELOG.md

@@ -5,6 +5,7 @@ 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]
+## [0.0.3] - 2022-01-16
 ### Added
 - `SimplePathReporter` error reporter.
 ### Changed
@@ -34,6 +35,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - The union codec
 - The pipe function and the composition codec
 
-[Unreleased]: https://github.com/facile-it/php-codec/compare/0.0.2...HEAD
+[Unreleased]: https://github.com/facile-it/php-codec/compare/0.0.3...HEAD
+[0.0.3]: https://github.com/facile-it/php-codec/compare/0.0.2...0.0.3
 [0.0.2]: https://github.com/facile-it/php-codec/compare/0.0.1...0.0.2
 [0.0.1]: https://github.com/facile-it/php-codec/releases/tag/0.0.1