Mark NSAutoreleasePool.Init() as must-dispose

Author: smoogipoo

osu.Framework/Platform/Apple/Native/NSAutoreleasePool.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using JetBrains.Annotations;
 
 namespace osu.Framework.Platform.Apple.Native
 {
@@ -19,6 +20,7 @@ internal NSAutoreleasePool(IntPtr handle)
         private static readonly IntPtr sel_init = Selector.Get("init");
         private static readonly IntPtr sel_drain = Selector.Get("drain");
 
+        [MustDisposeResource]
         public static NSAutoreleasePool Init()
             => new NSAutoreleasePool(Interop.SendIntPtr(Interop.SendIntPtr(class_pointer, sel_alloc), sel_init));