Moved SpectralConverter to the separate file

src/ImageSharp/Formats/Jpeg/Components/Decoder/SpectralConverter.cs

@@ -0,0 +1,16 @@
+// Copyright (c) Six Labors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+
+namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
+{
+    internal abstract class SpectralConverter : IDisposable
+    {
+        public abstract void InjectFrameData(JpegFrame frame, IRawJpegData jpegData);
+
+        public abstract void ConvertStrideBaseline();
+
+        public abstract void Dispose();
+    }
+}

src/ImageSharp/Formats/Jpeg/Components/Decoder/SpectralConverter{TPixel}.cs

@@ -13,15 +13,6 @@ using SixLabors.ImageSharp.PixelFormats;
 
 namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
 {
-    internal abstract class SpectralConverter : IDisposable
-    {
-        public abstract void InjectFrameData(JpegFrame frame, IRawJpegData jpegData);
-
-        public abstract void ConvertStrideBaseline();
-
-        public abstract void Dispose();
-    }
-
     internal sealed class SpectralConverter<TPixel> : SpectralConverter
         where TPixel : unmanaged, IPixel<TPixel>
     {