Remove deprecated tasks

This dataset uses `tasks`, which are deprecated and will raise an error after the next major release of `datasets`. See: https://github.com/huggingface/datasets/pull/6999

NIH-Chest-X-ray-dataset.py

@@ -17,7 +17,6 @@
 import os
 import datasets
 
-from datasets.tasks import ImageClassification
 from requests import get
 from pandas import read_csv