minor: prevent BC break in Runner (#6634)

.php-cs-fixer.php-lowest.php

@@ -26,6 +26,7 @@ $config->getFinder()->notPath([
     'src/DocBlock/Annotation.php',
     'src/Doctrine/Annotation/Tokens.php',
     'src/Tokenizer/Tokens.php',
+    'src/Runner/Runner.php',
 ]);
 
 $config->setRules([

src/Runner/Runner.php

@@ -68,7 +68,7 @@ final class Runner
      * @param list<FixerInterface>       $fixers
      */
     public function __construct(
-        \Traversable $finder,
+        $finder,
         array $fixers,
         DifferInterface $differ,
         ?EventDispatcherInterface $eventDispatcher,