update changelog

Author: thomasleveil

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Fixed
+
+- `opentelemetry-instrumentation-asgi` Fix UnboundLocalError local variable 'start' referenced before assignment 
+  ([#1889](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1889))
+
 ## Version 1.19.0/0.40b0 (2023-07-13)
 - `opentelemetry-instrumentation-asgi` Add `http.server.request.size` metric
   ([#1867](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1867))