Disable comparison since the reference decoders cannpt decode the image.

tests/ImageSharp.Tests/Formats/Bmp/BmpDecoderTests.cs

@@ -11,7 +11,6 @@ using Xunit;
 namespace SixLabors.ImageSharp.Tests
 {
     using SixLabors.ImageSharp.MetaData;
-    using SixLabors.ImageSharp.Tests.TestUtilities.ReferenceCodecs;
     using static TestImages.Bmp;
 
     public class BmpDecoderTests
@@ -97,7 +96,10 @@ namespace SixLabors.ImageSharp.Tests
             using (Image<TPixel> image = provider.GetImage(new BmpDecoder()))
             {
                 image.DebugSave(provider, "png");
-                image.CompareToOriginal(provider);
+
+                // TODO: Neither System.Drawing not MagickReferenceDecoder 
+                // can correctly decode this file.
+                // image.CompareToOriginal(provider);
             }
         }
     }