Fix call static methods

src/Connection/AsyncTcpConnection.php

@@ -422,7 +422,7 @@ class AsyncTcpConnection extends TcpConnection
             // Try to emit protocol::onConnect
             if ($this->protocol && method_exists($this->protocol, 'onConnect')) {
                 try {
-                    $this->protocol->onConnect($this);
+                    $this->protocol::onConnect($this);
                 } catch (Throwable $e) {
                     $this->error($e);
                 }

src/Connection/ConnectionInterface.php

@@ -58,7 +58,7 @@ abstract class ConnectionInterface
      * Application layer protocol.
      * The format is like this Workerman\\Protocols\\Http.
      *
-     * @var ?string
+     * @var ?class-string
      */
     public ?string $protocol = null;
 

src/Connection/TcpConnection.php

@@ -1019,7 +1019,7 @@ class TcpConnection extends ConnectionInterface implements JsonSerializable
         // Try to emit protocol::onClose
         if ($this->protocol && method_exists($this->protocol, 'onClose')) {
             try {
-                $this->protocol->onClose($this);
+                $this->protocol::onClose($this);
             } catch (Throwable $e) {
                 $this->error($e);
             }