Update CHANGELOG

Author: mmistakes

CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+### Changed
+- Relax Jekyll dependency to allow for version 4.0.
 
 ### Fixed
 - Fix MIME-type issues with Lunr search by renaming `search-data.json` to `lunr/lunr.store.js`. [#82](https://github.com/mmistakes/jekyll-theme-basically-basic/issues/82)