mark sendPacket as synchronized

I don't think there should be async issues but now it's better guaranteed

Author: mcmonkey4eva

src/main/java/com/denizenscript/depenizen/bungee/DepenizenConnection.java

@@ -105,7 +105,7 @@ public void run() {
 
     public HashMap<Long, ProxyPingEvent> proxyEventMap = new HashMap<>();
 
-    public void sendPacket(PacketOut packet) {
+    public synchronized void sendPacket(PacketOut packet) {
         try {
             ByteBuf buf = channel.alloc().buffer();
             packet.writeTo(buf);