Update CHANGELOG to release a new version (#472)

Author: edsonjab

CHANGELOG.md

@@ -1,3 +1,7 @@
+# Verion 3.5.1  (Feb 21, 2024)
+- [Chore] Dependency upgrades
+- [New](https://github.com/segmentio/analytics-java/pull/471) BlockingFlush, deregister parties upon message completion
+
 # Version 3.5.0 (Sept 27, 2023)
 - [New](https://github.com/segmentio/analytics-java/pull/446) Allow GsonBuilder to be passed in and used through Analytics and AnalyticsClient