docs(changelog): Update CHANGELOG-Colang.md to reflect fixed rail-processed message handling in Colang 2

Signed-off-by: Konstantin Lapine <[email protected]>

Author: lapinek

CHANGELOG-Colang.md

@@ -4,6 +4,12 @@ All notable changes to the Colang language and runtime will be documented in thi
 
 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).
 
+## [2.0-beta.7] - 2025-07-16
+
+### Fixed
+
+* Use processed user and bot messages after input/output rails transformations to prevent leakage of unfiltered data ([#1297](https://github.com/NVIDIA/NeMo-Guardrails/pull/1297)) by @lapinek
+
 ## [2.0-beta.6] - 2025-01-16
 
 ### Added