Fix Mailer contract returns (#36563)

Author: driesvints

src/Illuminate/Contracts/Mail/Factory.php

@@ -8,7 +8,7 @@ interface Factory
      * Get a mailer instance by name.
      *
      * @param  string|null  $name
-     * @return \Illuminate\Mail\Mailer
+     * @return \Illuminate\Contracts\Mail\Mailer
      */
     public function mailer($name = null);
 }

src/Illuminate/Mail/MailManager.php

@@ -63,7 +63,7 @@ public function __construct($app)
      * Get a mailer instance by name.
      *
      * @param  string|null  $name
-     * @return \Illuminate\Mail\Mailer
+     * @return \Illuminate\Contracts\Mail\Mailer
      */
     public function mailer($name = null)
     {

src/Illuminate/Support/Testing/Fakes/MailFake.php

@@ -276,7 +276,7 @@ protected function queuedMailablesOf($type)
      * Get a mailer instance by name.
      *
      * @param  string|null  $name
-     * @return \Illuminate\Mail\Mailer
+     * @return \Illuminate\Contracts\Mail\Mailer
      */
     public function mailer($name = null)
     {