Convert Input to Request facade

Laravel 5.2 no longer registers the `Input` facade by default. While
still available in Laravel 5, the `Input` facade is removed in
Laravel 6.

app/Http/Controllers/Admin/helpdesk/FormController.php

@@ -14,7 +14,7 @@ use Form;
 // Class
 use Illuminate\Http\Request;
 use Illuminate\Support\Str;
-use Input;
+use Illuminate\Support\Facades\Request as Input;
 use Lang;
 use Redirect;