Prepare 21.1.0 release.

Author: HexDecimal

CHANGELOG.md

@@ -6,6 +6,8 @@ This project adheres to [Semantic Versioning](https://semver.org/) since version
 
 ## [Unreleased]
 
+## [21.1.0] - 2026-04-04
+
 ### Added
 
 - `MouseButtonEvent.integer_position` property.

tcod/event.py

@@ -656,7 +656,7 @@ class MouseButtonEvent(Event):
     def integer_position(self) -> Point[int]:
         """Integer coordinates of this event.
 
-        .. versionadded:: Unreleased
+        .. versionadded:: 21.1
         """
         x, y = self.position
         return Point(floor(x), floor(y))