Remove old outdated header.

tests/Avalonia.Controls.UnitTests/WindowTests.cs

@@ -1,9 +1,3 @@
-// -----------------------------------------------------------------------
-// <copyright file="WindowTests.cs" company="Steven Kirk">
-// Copyright 2015 MIT Licence. See licence.md for more information.
-// </copyright>
-// -----------------------------------------------------------------------
-
 using System;
 using System.Collections.Generic;
 using System.Threading.Tasks;