Remove unnecessary transform.

Former-commit-id: 8b2f3cc3c3f3b433a43ebba426315b4259b3a963
Former-commit-id: 67bafb9926860171dcfeb87374b68184dd8da3b1
Former-commit-id: 6754ed62a6a80d72c4ac4b742c3d42d47e533242

src/ImageProcessor/Formats/Gif/GifEncoder.cs

@@ -139,7 +139,7 @@ namespace ImageProcessor.Formats
                 i =>
                     {
                         int offset = i * 3;
-                        Bgra32 color = Color.ToNonPremultiplied(pallete[i]);
+                        Bgra32 color = pallete[i];
 
                         colorTable[offset] = color.R;
                         colorTable[offset + 1] = color.G;