[9.x] Refactor some closure to arrow functions (#42610)

Author: reziamini

src/Illuminate/Auth/AuthManager.php

@@ -50,9 +50,7 @@ public function __construct($app)
     {
         $this->app = $app;
 
-        $this->userResolver = function ($guard = null) {
-            return $this->guard($guard)->user();
-        };
+        $this->userResolver = fn ($guard = null) => $this->guard($guard)->user();
     }
 
     /**
@@ -204,9 +202,7 @@ public function shouldUse($name)
 
         $this->setDefaultDriver($name);
 
-        $this->userResolver = function ($name = null) {
-            return $this->guard($name)->user();
-        };
+        $this->userResolver = fn ($name = null) => $this->guard($name)->user();
     }
 
     /**

src/Illuminate/Auth/AuthServiceProvider.php

@@ -46,9 +46,7 @@ protected function registerAuthenticator()
      */
     protected function registerUserResolver()
     {
-        $this->app->bind(AuthenticatableContract::class, function ($app) {
-            return call_user_func($app['auth']->userResolver());
-        });
+        $this->app->bind(AuthenticatableContract::class, fn ($app) => call_user_func($app['auth']->userResolver()));
     }
 
     /**