[libgdx] Fix SequenceTimeline JSON parsing

"stop" -> "hold"

spine-libgdx/spine-libgdx/src/com/esotericsoftware/spine/SkeletonJson.java

@@ -937,7 +937,7 @@ public class SkeletonJson extends SkeletonLoader {
 							for (int frame = 0; keyMap != null; keyMap = keyMap.next, frame++) {
 								float delay = keyMap.getFloat("delay", lastDelay);
 								timeline.setFrame(frame, keyMap.getFloat("time", 0),
-									SequenceMode.valueOf(keyMap.getString("mode", "stop")), keyMap.getInt("index", 0), delay);
+									SequenceMode.valueOf(keyMap.getString("mode", "hold")), keyMap.getInt("index", 0), delay);
 								lastDelay = delay;
 							}
 							timelines.add(timeline);