Update Microsoft.Toolkit.Uwp.UI.Behaviors/Keyboard/KeyDownTriggerBehavior.cs

Co-authored-by: Michael Hawker MSFT (XAML Llama) <24302614+michael-hawker@users.noreply.github.com>

Microsoft.Toolkit.Uwp.UI.Behaviors/Keyboard/KeyDownTriggerBehavior.cs

@@ -17,7 +17,7 @@ namespace Microsoft.Toolkit.Uwp.UI.Behaviors
         /// Identifies the <see cref="Key"/> property.
         /// </summary>
         public static readonly DependencyProperty KeyProperty = DependencyProperty.Register(
-            "Key",
+            nameof(Key),
             typeof(VirtualKey),
             typeof(KeyDownTriggerBehavior),
             new PropertyMetadata(null));