[Foundation] Fix return type for NSUrlSessionHandler.AutomaticDecompression. Fixes #13576. (#13577)

This was probably a c&p error.

Fixes https://github.com/xamarin/xamarin-macios/issues/13576.

src/Foundation/NSUrlSessionHandler.cs

@@ -532,7 +532,7 @@ namespace Foundation {
 
 #if NET
 		// Properties that will be called by the default HttpClientHandler
-		public bool AutomaticDecompression {
+		public DecompressionMethods AutomaticDecompression {
 			get => throw new PlatformNotSupportedException ();
 			set => throw new PlatformNotSupportedException ();
 		}