Boston housing data ethical problem - should be removed from training material

https://github.com/GoogleCloudPlatform/training-data-analyst/blob/cd10f8d2eda741f738b74a4300790be4a56f501e/courses/machine_learning/deepdive2/machine_learning_in_the_enterprise/labs/sdk_custom_tabular_regression_online_explain.ipynb?short_path=d762eca#L32

See https://scikit-learn.org/stable/modules/generated/sklearn.datasets.load_boston.html for reasons why this dataset is deprecated.