Fix Bossbar: entity id is Long

Author: KCodeYT

bedrock/bedrock-v291/src/main/java/com/nukkitx/protocol/bedrock/v291/serializer/BossEventSerializer_v291.java

@@ -48,7 +48,7 @@ public void serialize(ByteBuf buffer, BedrockPacketHelper helper, BossEventPacke
 
     @Override
     public void deserialize(ByteBuf buffer, BedrockPacketHelper helper, BossEventPacket packet) {
-        packet.setBossUniqueEntityId(VarInts.readInt(buffer));
+        packet.setBossUniqueEntityId(VarInts.readLong(buffer));
         BossEventPacket.Action action = BossEventPacket.Action.values()[VarInts.readUnsignedInt(buffer)];
         packet.setAction(action);