Pluggable Widgets Tools v10.21.0: Update changelog (#122)

This is an automated PR that merges changelog update to master.

Author: weirdwater

packages/pluggable-widgets-tools/CHANGELOG.md

@@ -6,6 +6,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ## [Unreleased]
 
+## [10.21.0] - 2025-03-27
+
 ### Added
 
 -   We added support for action variables, introduced in Mendix 10.21.