CHANGELOG: move #4466 PR to unreleased

Author: xrmx

CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Fix user agent in OTLP HTTP metrics exporter
   ([#4475](https://github.com/open-telemetry/opentelemetry-python/pull/4475))
+- Improve performance of baggage operations
+  ([#4466](https://github.com/open-telemetry/opentelemetry-python/pull/4466))
 
 ## Version 1.31.0/0.52b0 (2025-03-12)
 
@@ -41,8 +43,6 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#4458](https://github.com/open-telemetry/opentelemetry-python/pull/4458))
 - pylint-ci updated python version to 3.13
   ([#4450](https://github.com/open-telemetry/opentelemetry-python/pull/4450))
-- Improve performance of baggage operations
-  ([#4466](https://github.com/open-telemetry/opentelemetry-python/pull/4466))
 
 ## Version 1.30.0/0.51b0 (2025-02-03)