fix checksum of IEND chunk

src/main/java/eu/jonahbauer/raytracing/render/ImageFormat.java

@@ -41,6 +41,7 @@ public enum ImageFormat {
         private static final int IHDR_TYPE = 0x49484452;
         private static final int IDAT_TYPE = 0x49444154;
         private static final int IEND_TYPE = 0x49454E44;
+        private static final int IEND_CRC = 0xAE426082;
 
         @Override
         public void write(@NotNull Canvas image, @NotNull OutputStream out) throws IOException {
@@ -101,7 +102,7 @@ public enum ImageFormat {
         private void writeIEND(@NotNull Canvas image, @NotNull DataOutputStream data) throws IOException {
             data.writeInt(0);
             data.writeInt(IEND_TYPE);
-            data.writeInt(0);
+            data.writeInt(IEND_CRC);
         }
 
         private static class NoCloseDataOutputStream extends DataOutputStream {