Fixed DocBlock return type (#565)

* Fixed DocBlock return type

* Update Provider.php

Co-authored-by: Taylor Otwell <taylor@laravel.com>

src/Contracts/Provider.php

@@ -7,7 +7,7 @@ interface Provider
     /**
      * Redirect the user to the authentication page for the provider.
      *
-     * @return \Symfony\Component\HttpFoundation\RedirectResponse
+     * @return \Symfony\Component\HttpFoundation\RedirectResponse|\Illuminate\Http\RedirectResponse
      */
     public function redirect();