fix duplicate braces

src/Avalonia.Controls.ColorPicker/ColorView/ColorView.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using Avalonia.Controls.Converters;
 using Avalonia.Controls.Metadata;
@@ -154,8 +154,6 @@ namespace Avalonia.Controls
                         {
                             newPaletteColors.Add(palette.GetColor(colorIndex, shadeIndex));
                         }
-                        }
-                        }
                     }
 
                     SetCurrentValue(PaletteColorsProperty, newPaletteColors);