Update CHANGELOG for version 2.0.4

Author: mlaferrera

CHANGELOG.md

@@ -5,15 +5,15 @@ 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).
 
-## Unreleased
+## [2.0.4] - 2019-03-29
 
 ### Added
 
 - `Stoq.reconstruct_all_subresponses()` method to allow for reconstructing `StoqResponse` objects iteratively (@maydewd)
 
 ### Changed
 
-- Force payload content to be of type bytes
+- Force payload content to be of type `bytes`
 
 ## [2.0.3] - 2019-02-15