fix: 移除Implicit nullable parameters，php8.4中显式声明null

Author: runoob-coder

src/Commands/DumpServerCommand.php

@@ -30,7 +30,7 @@ class DumpServerCommand extends Command
      */
     protected $server;
 
-    public function __construct(string $name = null)
+    public function __construct(?string $name = null)
     {
         parent::__construct($name);
 

src/Dumper.php

@@ -24,7 +24,7 @@ class Dumper
      * @param  \Symfony\Component\VarDumper\Server\Connection|null  $connection
      * @return void
      */
-    public function __construct(Connection $connection = null)
+    public function __construct(?Connection $connection = null)
     {
         $this->connection = $connection;
     }

src/RequestContextProvider.php

@@ -35,7 +35,7 @@ class RequestContextProvider implements ContextProviderInterface
      *
      * @param Request $currentRequest
      */
-    public function __construct(Request $currentRequest = null)
+    public function __construct(?Request $currentRequest = null)
     {
         $this->currentRequest = $currentRequest;
         $this->cloner = new VarCloner;