More return type fixes

Author: nicolas-grekas

Loader/YamlFileLoader.php

@@ -13,7 +13,6 @@
 
 use Symfony\Component\DependencyInjection\Alias;
 use Symfony\Component\DependencyInjection\Argument\AbstractArgument;
-use Symfony\Component\DependencyInjection\Argument\ArgumentInterface;
 use Symfony\Component\DependencyInjection\Argument\BoundArgument;
 use Symfony\Component\DependencyInjection\Argument\IteratorArgument;
 use Symfony\Component\DependencyInjection\Argument\ServiceClosureArgument;
@@ -803,9 +802,7 @@ private function validate($content, string $file): ?array
     }
 
     /**
-     * Resolves services.
-     *
-     * @return array|string|Reference|ArgumentInterface
+     * @return mixed
      */
     private function resolveServices($value, string $file, bool $isParameter = false)
     {

Tests/Fixtures/includes/ProjectWithXsdExtension.php

@@ -2,7 +2,7 @@
 
 class ProjectWithXsdExtension extends ProjectExtension
 {
-    public function getXsdValidationBasePath()
+    public function getXsdValidationBasePath(): string
     {
         return __DIR__.'/schema';
     }