CHANGELOG: forgot date

Author: dlech

CHANGELOG.md

@@ -4,7 +4,7 @@ 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).
 
-## [1.0.0-alpha.3]
+## [1.0.0-alpha.3] - 2021-04-09
 ### Changed
 - Print BLE download progress after chunk is complete instead of before.
 ### Fixed