Tag Release v0.4.0

Author: jan-di

CHANGELOG.md

@@ -5,6 +5,8 @@ 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]
+
+## [0.4.0] - 2022-05-05
 ### Added
 - Open Metrics/Prometheus endpoint
 - Add grace time options to ignore errors on newly started targets