CHANGELOG.md: add unreleased notes

Author: alanorth

CHANGELOG.md

@@ -4,6 +4,10 @@ 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
+### Updated
+- Add more formats to `NormalizeDOIs` curation task
+
 ## [7.6.1.2] - 2024-04-25
 ### Changed
 - Remove reporting from curation tasks since "results" are enough