Update changelog

Author: NN---

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+- Type indent parameter in to_json
+- ([#4402](https://github.com/open-telemetry/opentelemetry-python/pull/4402))
 - Always setup logs sdk, OTEL_PYTHON_LOGGING_AUTO_INSTRUMENTATION_ENABLED only controls python `logging` module handler setup
   ([#4340](https://github.com/open-telemetry/opentelemetry-python/pull/4340))
 - Add `attributes` field in `metrics.get_meter` wrapper function