Fix Application afterLoadingEnvironment method (#39982)

Author: seriquynh

src/Illuminate/Foundation/Application.php

@@ -230,7 +230,7 @@ public function bootstrapWith(array $bootstrappers)
      */
     public function afterLoadingEnvironment(Closure $callback)
     {
-        return $this->afterBootstrapping(
+        $this->afterBootstrapping(
             LoadEnvironmentVariables::class, $callback
         );
     }