Update v3.0.0 release date (#213)

Since the original release was delayed due to the packaging step
failing (see #210).

(I've used 28th not 27th for the date, since we/the automation use
UTC dates in the changelog.)

Author: edmorley

CHANGELOG.md

@@ -7,7 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-## [3.0.0] - 2024-02-23
+## [3.0.0] - 2024-02-28
 
 ### Added