Fixed wasdk Color reference

Author: Avid29

components/ColorAnalyzer/samples/ContrastHelper/ContrastOptionsPane.xaml.cs

@@ -5,10 +5,15 @@
 #if !WINDOWS_UWP
 using Microsoft.UI.Xaml.Media.Imaging;
 #elif WINDOWS_UWP
-using Windows.UI;
 using Windows.UI.Xaml.Media.Imaging;
 #endif
 
+#if WINUI3
+using Microsoft.UI;
+#endif
+
+using Windows.UI;
+
 namespace ColorAnalyzerExperiment.Samples;
 
 [ToolkitSampleOptionsPane(nameof(TextBlockContrastSample))]