Add kaboom image for future testing

tests/ImageSharp.Tests/TestImages.cs

@@ -35,6 +35,7 @@ namespace SixLabors.ImageSharp.Tests
             public const string Rgb48BppInterlaced = "Png/rgb-48bpp-interlaced.png";
             public const string SnakeGame = "Png/SnakeGame.png";
             public const string Icon = "Png/icon.png";
+            public const string Kaboom = "Png/kaboom.png";
 
             // Filtered test images from http://www.schaik.com/pngsuite/pngsuite_fil_png.html
             public const string Filter0 = "Png/filter0.png";