Use non-animated gif in benchmark [skip ci]

System.Drawing doesn't decode or encode all animated gif frames.


Former-commit-id: 7b19025c55d57da7ec310bcca9d3ce3d3e3859e6
Former-commit-id: b0a20491cb4b0b9f6358a6d216e1b2e5f2b0b0ae
Former-commit-id: 51a8546a8881233a79baae83c937f98252821850

tests/ImageProcessorCore.Benchmarks/Image/Decode.cs

@@ -28,7 +28,7 @@ namespace ImageProcessorCore.Benchmarks.Image
             }
             if (gifBytes == null)
             {
-                gifBytes = File.ReadAllBytes("../ImageProcessorCore.Tests/TestImages/Formats/Gif/giphy.gif");
+                gifBytes = File.ReadAllBytes("../ImageProcessorCore.Tests/TestImages/Formats/Gif/rings.gif");
             }
             if (jpegBytes == null)
             {

tests/ImageProcessorCore.Benchmarks/Image/Encode.cs

@@ -43,7 +43,7 @@ namespace ImageProcessorCore.Benchmarks.Image
 
             if (gifStream == null)
             { 
-                gifStream = File.OpenRead("../ImageProcessorCore.Tests/TestImages/Formats/Gif/giphy.gif");
+                gifStream = File.OpenRead("../ImageProcessorCore.Tests/TestImages/Formats/Gif/rings.gif");
                 gifCore = new CoreImage(gifStream);
                 gifStream.Position = 0;
                 gifDrawing = Image.FromStream(gifStream);