Trim model class name (#25849)

When passing php class names in middleware, for example
```
->middleware('can:create, App\Models\JobDocument);
```

Developer can accidentally add a whitespace before class name.
This whitespace will cause the linked policy to not found and
cause a 403 http response.

src/Illuminate/Auth/Middleware/Authorize.php

@@ -72,7 +72,7 @@ protected function getGateArguments($request, $models)
      */
     protected function getModel($request, $model)
     {
-        return $this->isClassName($model) ? $model : $request->route($model, $model);
+        return $this->isClassName($model) ? trim($model) : $request->route($model, $model);
     }
 
     /**