Dataset in tpu_speed_data_pipelines.ipynb is not accessible

In analyst/tree/master/courses/machine_learning/deepdive2/production_ml/labs/tpu_speed_data_pipelines.ipynb, there is an issue with the dataset.

Those datasets seem not to work:
training_images_file = 'gs://mnist-public/train-images-idx3-ubyte'
training_labels_file = 'gs://mnist-public/train-labels-idx1-ubyte'
validation_images_file = 'gs://mnist-public/t10k-images-idx3-ubyte'
validation_labels_file = 'gs://mnist-public/t10k-labels-idx1-ubyte'

When running the next sell loading the dataset, we get error 403: The billing account for the owning project is disabled in state closed

Open courses/machine_learning/deepdive2/production_ml/labs/tpu_speed_data_pipelines.ipynb and inspect the cell that loads the four gs://mnist-public dataset paths. Reproduce the 403 billing-account error first; the issue is resolved when the notebook can load the training and validation data without that error.

Written by the indexing model from the issue text.