chore: add v1.6.6 to changelog

Author: pilimartinez

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).
 
+## [v1.6.6](https://github.com/checkly/terraform-provider-checkly/releases/tag/v1.6.6) - 2023-06-06
+### Added
+- Support new private dashboards [#ba48b60](https://github.com/checkly/terraform-provider-checkly/commit/ba48b60)
+
 ## [v1.6.3](https://github.com/checkly/terraform-provider-checkly/releases/tag/v1.6.3) - 2022-10-26
 
 ### Added