remove unnecessary usings after merge

Author: InfernoDragon0

COTL_API/CustomSkins/CustomSkinManager.cs

@@ -1,4 +1,3 @@
-using System;
 using HarmonyLib;
 using Spine;
 using Spine.Unity;

COTL_API/Helpers/KeyCodes.cs

@@ -1,5 +1,4 @@
-using System;
-using UnityEngine;
+using UnityEngine;
 
 namespace COTL_API.Helpers;
 

COTL_API/Patches/SettingsPatches.cs

@@ -1,5 +1,4 @@
-using System;
-using COTL_API.CustomSkins;
+using COTL_API.CustomSkins;
 using HarmonyLib;
 using Lamb.UI;
 using Lamb.UI.MainMenu;