fix xy color conversion using srgb instead of rgb.

models/colorxy.go

@@ -177,7 +177,7 @@ func hsToXY(hue, sat float64) ColorXY {
 	green := float64(green255) / 255.0
 	blue := float64(blue255) / 255.0
 
-	return screenRGBToXY(red, green, blue)
+	return rgbToXY(red, green, blue)
 }
 
 func rgbToXY(red float64, green float64, blue float64) ColorXY {