Move cherry-picked changelog entry into Unreleased section

CHANGELOG.md

@@ -5,10 +5,13 @@ 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).
 
-## Version 1.28.1/0.49b1 (2024-11-08)
+## Unreleased
 
 - Fix crash exporting a log record with None body
   ([#4276](https://github.com/open-telemetry/opentelemetry-python/pull/4276))
+
+## Version 1.28.1/0.49b1 (2024-11-08)
+
 - Fix metrics export with exemplar and no context and filtering observable instruments
   ([#4251](https://github.com/open-telemetry/opentelemetry-python/pull/4251))
 - Fix recursion error with sdk disabled and handler added to root logger