The clear_3d_labels() call does not clear the labels in the scene.

### Checklist

- [X] I have searched for [similar issues](https://github.com/isl-org/Open3D/issues).
- [X] For Python issues, I have tested with the [latest development wheel](http://www.open3d.org/docs/latest/getting_started.html#development-version-pip).
- [X] I have checked the [release documentation](http://www.open3d.org/docs/release/) and the [latest documentation](http://www.open3d.org/docs/latest/) (for `master` branch).

### My Question

I am using SceneWidget and in there I am rendering 3d text using `add_3d_label()` call. Now I would like to update the text as I translate the mesh that I have in the scene, for which I am trying to use `clear_3d_labels()`, however, I get the following error when I am making the call over the `o3d.visualization.rendering.Open3DScene` object. The error is as follow -

```
AttributeError: 'open3d.cuda.pybind.visualization.rendering.Open3DS' object has no attribute 'clear_3d_labels'
```

Is there the some issue with the usage or the issue is with function?