sagemaker-countycensusclustering.ipynb failed CI

Link to the notebook:
https://github.com/aws/amazon-sagemaker-examples/blob/master/introduction_to_applying_machine_learning/US-census_population_segmentation_PCA_Kmeans/sagemaker-countycensusclustering.ipynb

Error:

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Exception encountered at "In [1]":
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ModuleNotFoundError Traceback (most recent call last)
in
11 import matplotlib.pyplot as plt
12 import matplotlib
---> 13 import seaborn as sns
14 matplotlib.style.use('ggplot')
15 import pickle, gzip, urllib, json

ModuleNotFoundError: No module named 'seaborn'