update changelog

Author: keith-decker

util/opentelemetry-util-genai/CHANGELOG.md

@@ -6,7 +6,7 @@ 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
-
+- Enrich ToolCall type ([#4218](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4218))
 - Add support for emitting inference events and enrich message types. ([#3994](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3994))
 - Add support for `server.address`, `server.port` on all signals and additional metric-only attributes
   ([#4069](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4069))