Use singleton during Schedule creation to allow "resolving" callbacks (…

…#20933)

* Use singleton during Schedule creation to allow "resolving" callbacks

* Update Kernel.php

src/Illuminate/Foundation/Console/Kernel.php

@@ -97,7 +97,11 @@ public function __construct(Application $app, Dispatcher $events)
      */
     protected function defineConsoleSchedule()
     {
-        $this->app->instance(Schedule::class, $schedule = new Schedule());
+        $this->app->singleton(Schedule::class, function ($app) {
+            return new Schedule;
+        });
+
+        $schedule = $this->app->make(Schedule::class);
 
         $this->schedule($schedule);
     }