Add another test case for Fax4 compressed with min is black

tests/ImageSharp.Tests/Formats/Tiff/TiffDecoderTests.cs

@@ -611,6 +611,8 @@ namespace SixLabors.ImageSharp.Tests.Formats.Tiff
 
         [Theory]
         [WithFile(Fax4Compressed, PixelTypes.Rgba32)]
+        [WithFile(Fax4Compressed2, PixelTypes.Rgba32)]
+        [WithFile(Fax4CompressedMinIsBlack, PixelTypes.Rgba32)]
         [WithFile(Fax4CompressedLowerOrderBitsFirst, PixelTypes.Rgba32)]
         [WithFile(Calliphora_Fax4Compressed, PixelTypes.Rgba32)]
         public void TiffDecoder_CanDecode_Fax4Compressed<TPixel>(TestImageProvider<TPixel> provider)

tests/ImageSharp.Tests/TestImages.cs

@@ -762,6 +762,7 @@ namespace SixLabors.ImageSharp.Tests
             public const string Fax4Compressed = "Tiff/basi3p02_fax4.tiff";
             public const string Fax4Compressed2 = "Tiff/CCITTGroup4.tiff";
             public const string Fax4CompressedLowerOrderBitsFirst = "Tiff/basi3p02_fax4_lowerOrderBitsFirst.tiff";
+            public const string Fax4CompressedMinIsBlack = "Tiff/CCITTGroup4_minisblack.tiff";
 
             public const string CcittFax3AllTermCodes = "Tiff/ccitt_fax3_all_terminating_codes.tiff";
             public const string CcittFax3AllMakeupCodes = "Tiff/ccitt_fax3_all_makeup_codes.tiff";

tests/Images/Input/Tiff/CCITTGroup4_minisblack.tiff

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:6c12c96059a6214739fe836572bce6912dcf4a0d2ff389c840f0d2daa4465f55
+size 11637