chore: add changelog

Author: diogosilva30

CHANGELOG.md

@@ -13,6 +13,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- `opentelemetry-instrumentation-httpx`: fix missing metric response attributes when tracing is disabled
+  ([#3615](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3615))
 - `opentelemetry-instrumentation-asgi`: fix excluded_urls in instrumentation-asgi
   ([#3567](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/3567))
 - `opentelemetry-resource-detector-containerid`: make it more quiet on platforms without cgroups