Updated changelog and package version for Netcode in anticipation of v2.12.0 release

Author: svc-netcode-sdk

com.unity.netcode.gameobjects/CHANGELOG.md

@@ -6,7 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 
 Additional documentation and release notes are available at [Multiplayer Documentation](https://docs-multiplayer.unity3d.com).
 
-## [Unreleased]
+## [2.12.0] - 2026-05-24
 
 ### Added
 
@@ -20,18 +20,6 @@ Additional documentation and release notes are available at [Multiplayer Documen
 
 - Deprecated a number of methods that were no longer valid or being used. (#3987)
 
-### Removed
-
-
-### Fixed
-
-
-### Security
-
-
-### Obsolete
-
-
 ### [2.11.2] - 2026-05-01
 
 ### Fixed