fix new phpstan issues

src/Bundle/ChillMainBundle/Form/Type/DataTransformer/MultipleObjectsToIdTransformer.php

@@ -31,8 +31,6 @@ class MultipleObjectsToIdTransformer implements DataTransformerInterface
      * Transforms a string (id) to an object (item).
      *
      * @param mixed $array
-     *
-     * @return ArrayCollection
      */
     public function reverseTransform($array)
     {
@@ -53,10 +51,8 @@ class MultipleObjectsToIdTransformer implements DataTransformerInterface
      * Transforms an object (use) to a string (id).
      *
      * @param array $array
-     *
-     * @return ArrayCollection
      */
-    public function transform($array)
+    public function transform($array): array
     {
         $ret = [];