Chore: Preparation for 1.14.0 release (#3556)

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I don't have github access to modify release branches directly, so
creating this PR here.

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## Backport

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Author: SamuelBellomo

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]
+## [1.14.0] - 2025-07-21
 
 ### Added
 

com.unity.netcode.gameobjects/package.json

@@ -2,7 +2,7 @@
     "name": "com.unity.netcode.gameobjects",
     "displayName": "Netcode for GameObjects",
     "description": "Netcode for GameObjects is a high-level netcode SDK that provides networking capabilities to GameObject/MonoBehaviour workflows within Unity and sits on top of underlying transport layer.",
-    "version": "1.13.1",
+    "version": "1.14.0",
     "unity": "2021.3",
     "dependencies": {
       "com.unity.nuget.mono-cecil": "1.10.1",