Changed return type to void for Hyperf\Event\Contract\ListenerInterface::process(). (#4611)

Author: limingxinleo

src/Listener/InitSenderListener.php

@@ -32,7 +32,7 @@ public function listen(): array
         ];
     }
 
-    public function process(object $event)
+    public function process(object $event): void
     {
         if ($this->container->has(Sender::class)) {
             $sender = $this->container->get(Sender::class);

src/Listener/OnPipeMessageListener.php

@@ -39,7 +39,7 @@ public function listen(): array
      * Handle the Event when the event is triggered, all listeners will
      * complete before the event is returned to the EventDispatcher.
      */
-    public function process(object $event)
+    public function process(object $event): void
     {
         if ($event instanceof OnPipeMessage && $event->data instanceof SenderPipeMessage) {
             /** @var SenderPipeMessage $message */