Updates CHANGELOG for version 0.3.0.

CHANGELOG.md

@@ -5,6 +5,16 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [0.3.0] - 2019-07-27
+
+### Added
+
+- Support and tests for TOTP with SHA256 and SHA512
+
+### Fixed
+
+- Crystal 0.28.0 changed the first argument for `OpenSSL::HMAC#digest` from a symbol to a type of `OpenSSL::Algorithm`. Updated this within the library thanks to [@Xosmond](https://github.com/Xosmond).
+
 ## [0.2.0] - 2019-03-28
 
 ### Fixed