use square bracket syntax to modify array

Signed-off-by: Hamid Dehnavi <hamid.dev.pro@gmail.com>

apps/settings/lib/Controller/UsersController.php

@@ -220,7 +220,7 @@ class UsersController extends Controller {
 
 				foreach ($groups as $key => $group) {
 					// $userCount += (int)$group['usercount'];
-					array_push($groupsNames, $group['name']);
+					$groupsNames[] = $group['name'];
 					// we prevent subadmins from looking up themselves
 					// so we lower the count of the groups he belongs to
 					if (array_key_exists($group['id'], $userGroups)) {