Fixup changelog for 2.8.0 release

Correct date.

Keep the [Unreleased] section at the top.

Author: Techcable

CHANGELOG.md

@@ -4,7 +4,9 @@ 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/).
 
-## 2.8.0 - 2023-06-16
+## [Unreleased]
+
+## 2.8.0 - 2023-08-26
 
 * Call of deprecated `err.description()` replaced with `err.to_string()`.
 * Avoided all catchable panics in async drain thread.