Update StackNavigationManager.cs

Author: Tamilarasan-Paranthaman

src/Core/src/Platform/Android/Navigation/StackNavigationManager.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Collections.Generic;
-using System.Threading.Tasks;
 using Android.Content;
 using Android.OS;
 using Android.Views;
@@ -329,6 +328,8 @@ void UpdateNavigationStack(IReadOnlyList<IView> newPageStack)
 
 		public virtual void Disconnect()
 		{
+			_navigationQueue.Clear();
+
 			if (IsNavigating)
 				NavigationFinished(NavigationView);