Fix deprecated message

> Method "Psr\Log\LoggerAwareInterface::setLogger()" might add "void" as a native return type declaration in the future. Do the same in implementation "Readability\Readability" now to avoid errors or add an explicit @return annotation to suppress this message.

src/Readability.php

@@ -187,6 +187,9 @@ class Readability implements LoggerAwareInterface
         $this->loadHtml();
     }
 
+    /**
+     * @return void
+     */
     public function setLogger(LoggerInterface $logger)
     {
         $this->logger = $logger;