Fixed a typo in phpdoc block (#48296)

It will fix a little typo in the PHPDoc block of `excludedMiddleware` method in Route class

Author: back2Lobby

src/Illuminate/Routing/Route.php

@@ -1136,7 +1136,7 @@ public function withoutMiddleware($middleware)
     }
 
     /**
-     * Get the middleware should be removed from the route.
+     * Get the middleware that should be removed from the route.
      *
      * @return array
      */