Add changelog entry for Celery housekeeping

Assisted-by: GPT-5.4

Author: diogosilva30

CHANGELOG.md

@@ -26,6 +26,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#4461](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4461))
 - `opentelemetry-instrumentation-dbapi` Use `ObjectProxy` instead of `BaseObjectProxy` for `TracedCursorProxy` to restore iterability with wrapt 2.x
   ([#4427](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4427))
+- `opentelemetry-instrumentation-celery`: Add null guards and type-safe helper handling around Celery context propagation internals
+  ([#4505](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4505))
 - `opentelemetry-instrumentation-flask`: Clean up environ keys in `_teardown_request` to prevent duplicate execution
   ([#4341](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/4341))
 - `opentelemetry-instrumentation-flask`: Stop reading the deprecated (from 3.1) `flask.__version__` attribute; resolve the Flask version via `importlib.metadata`