use sudo apt-get update in courses/machine_learning/deepdive2/feature_engineering/solutions/4_keras_adv_feat_eng.ipynb

In order to properly install `graphviz` in [https://github.com/GoogleCloudPlatform/training-data-analyst/blob/master/courses/machine_learning/deepdive2/feature_engineering/solutions/4_keras_adv_feat_eng.ipynb](https://github.com/GoogleCloudPlatform/training-data-analyst/blob/master/courses/machine_learning/deepdive2/feature_engineering/solutions/4_keras_adv_feat_eng.ipynb)
We should first update. So the second cell should be
```
!sudo apt-get update && sudo apt-get install graphviz -y
```