Remove unnecessary transform.

Former-commit-id: dd5ed0335d63cbf91bc51dfd616d0e689774c1ca
Former-commit-id: ad926bc4a4ba3d597f0e839f1c91c0a3e7f51e9f
Former-commit-id: d8ecfc9db2c0b244503eec5b86d24c0da8b47af4

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;