polish: add changelog.

Author: eternalcuriouslearner

instrumentation-genai/opentelemetry-instrumentation-openai-v2/CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- Fix `ChoiceBuffer` crash on streaming tool-call deltas with `arguments=None`
+  ([#4350](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4350))
 - Fix `StreamWrapper` missing `.headers` and other attributes when using `with_raw_response` streaming
   ([#4113](https://github.com/open-telemetry/opentelemetry-python-contrib/issues/4113))
 - Add opt-in support for latest experimental semantic conventions (v1.37.0). Set