Update changelog

Author: ocelotl

CHANGELOG.md

@@ -5,6 +5,8 @@ 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).
 
 ## [Unreleased](https://github.com/open-telemetry/opentelemetry-python-contrib/compare/v0.18b0...HEAD)
+- Sync contribs with optional getters and setters
+  ([#372](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/372))
 - Updated instrumentations to use `opentelemetry.trace.use_span` instead of `Tracer.use_span()`
   ([#364](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/364))
 - `opentelemetry-propagator-ot-trace` Do not throw an exception when headers are not present