Open3d Python on Ubuntu failed to use web visualizer

### 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 a vscode remote Ubuntu server to run the Python (3.9) webvisualizer example (https://github.com/isl-org/Open3D/blob/master/examples/python/visualization/draw_webrtc.py) but have failed. This is what I got, any ideas how to debug? Any help would be much appreciated.