Fix Subuser welcome email

When calling `route('server.index')` it appends `/api/servers`

Not sure if this is a proper solution or not, but it fixes the issue.

Author: notAreYouScared

app/Notifications/AddedToServer.php

@@ -56,6 +56,6 @@ public function toMail($notifiable)
             ->greeting('Hello ' . $this->server->user . '!')
             ->line('You have been added as a subuser for the following server, allowing you certain control over the server.')
             ->line('Server Name: ' . $this->server->name)
-            ->action('Visit Server', route('server.index', $this->server->uuidShort));
+            ->action('Visit Server', url('/server/' . $this->server->uuidShort));
     }
 }