Update Finder.php

Corrected return type which causes following error with (psalm)[https://getpsalm.org/]
```
ERROR: PossiblyInvalidArgument - src/Command/Utils/CheckVendorDependencies.php:170:62 - Argument 1 of iterator_to_array expects Traversable, possibly different type array<mixed, Symfony\Component\Finder\SplFileInfo>|Iterator provided $directories = array_map($closure, iterator_to_array($finder->getIterator()));
```

Author: tarlepp

Finder.php

@@ -668,7 +668,7 @@ public function in($dirs)
      *
      * This method implements the IteratorAggregate interface.
      *
-     * @return \Iterator|SplFileInfo[] An iterator
+     * @return \Iterator|\SplFileInfo[] An iterator
      *
      * @throws \LogicException if the in() method has not been called
      */