chore: Add Unreleased Tag to CHANGELOG

Author: OS-ricardomoreirasilva

CHANGELOG.md

@@ -4,6 +4,8 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## [Unreleased]
+
 ## [2.1.2] - 2022-11-23
 ### Fixes
 - Fix: [iOS] When there are no keys associated with a store, return empty string instead of `nil`.