Remove UserInterface SF 5.4 deprecations (#204)

Fix #202

Author: alterphp

src/Model/AdminUser.php

@@ -74,6 +74,8 @@ public function getGroups(): Collection
 
     /**
      * {@inheritdoc}
+     *
+     * @return array
      */
     public function getRoles()
     {
@@ -88,6 +90,8 @@ public function getRoles()
 
     /**
      * {@inheritdoc}
+     *
+     * @return ?string
      */
     public function getPassword()
     {
@@ -96,6 +100,8 @@ public function getPassword()
 
     /**
      * {@inheritdoc}
+     *
+     * @return ?string
      */
     public function getSalt()
     {