chore: Switch to AwesomeAssertions

Author: MartinZikmund

src/Uno.UI.RuntimeTests/Tests/Microsoft_UI_Windowing/Given_AppWindow.cs

@@ -3,7 +3,7 @@
 using System.Reflection;
 using System.Threading.Tasks;
 using Combinatorial.MSTest;
-using FluentAssertions;
+using AwesomeAssertions;
 using Microsoft.UI.Windowing;
 using Microsoft.UI.Xaml;
 using Private.Infrastructure;