remove unused using

Author: stefannikolei

src/ImageSharp/Formats/Jpeg/Components/ColorConverters/JpegColorConverter.CmykArm64.cs

@@ -5,7 +5,6 @@
 using System.Runtime.InteropServices;
 using System.Runtime.Intrinsics;
 using System.Runtime.Intrinsics.Arm;
-using System.Runtime.Intrinsics.X86;
 
 namespace SixLabors.ImageSharp.Formats.Jpeg.Components;