add .contains() (#29)

Author: eyas-ranjous

CHANGELOG.md

@@ -5,6 +5,10 @@ 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]
+## [4.3.0] - 2025-09-17
+### Added
+- .contains() to check if the queue contains a specific element.
+
 ## [4.2.5] - 2025-09-08
 ### Fixed
 - return null in type definition for functions.