[5.x] Class "DB" not found issue (statamic#11911)

* fix: Class "DB" not found issue

* fix: lint issue

Author: leganz

src/Auth/Eloquent/UserGroup.php

@@ -2,6 +2,7 @@
 
 namespace Statamic\Auth\Eloquent;
 
+use Illuminate\Support\Facades\DB;
 use Statamic\Auth\File\UserGroup as FileUserGroup;
 use Statamic\Facades\User;
 
@@ -50,7 +51,7 @@ public function queryUsers()
 
     protected function getUserIds()
     {
-        return \DB::connection(config('statamic.users.database'))
+        return DB::connection(config('statamic.users.database'))
             ->table(config('statamic.users.tables.group_user', 'group_user'))
             ->where('group_id', $this->id())
             ->pluck('user_id');