Modernize private property declarations in Threaded classes

I previously avoided this due to being unsure of the effects; however, it's clear that we already use typed properties on Threaded things in other places anyway, and the only known issues are with uninit properties, and arrays.

src/network/mcpe/raklib/RakLibServer.php

@@ -40,8 +40,7 @@ use function register_shutdown_function;
 use const PTHREADS_INHERIT_NONE;
 
 class RakLibServer extends Thread{
-	/** @var InternetAddress */
-	private $address;
+	private InternetAddress $address;
 
 	/** @var \ThreadedLogger */
 	protected $logger;
@@ -63,8 +62,8 @@ class RakLibServer extends Thread{
 	protected $serverId;
 	/** @var int */
 	protected $maxMtuSize;
-	/** @var int */
-	private $protocolVersion;
+
+	private int $protocolVersion;
 
 	/** @var SleeperNotifier */
 	protected $mainThreadNotifier;