"Classifying Images with a Linear Model" lab requires graphviz Debian package install before any GUI steps

The 10th code cell would display the linear NN model's graph.
`tf.keras.utils.plot_model(model, show_shapes=True, show_layer_names=False)`


That fails with
`('You must install pydot (`pip install pydot`) and install graphviz (see instructions at https://graphviz.gitlab.io/download/) ', 'for plot_model/model_to_dot to work.')`

However `!pip install pydot graphviz` reveals that those python packages are installed in the notebook's python venv. However the underlying jupyter notebook's VM doesn't have the `graphviz` Debian package installed.

Trying `sudo apt install graphviz` failed because the GUI had apt locked. So this step should be done possibly right after the repo cloning, or even before that.