Fix img classification tests

[nateraw]

What does this PR do?

Fixes unittest issues from #13134. First there was an issue of missing torchvision, which was resolved with #13438 , but when that didn't fix it we skipped test_run_image_classification with #13451

Additionally, I added a test dataset to our internal testing org on huggingface.co, which is what we're using in the test now. Its 50 examples from the cats_vs_dogs dataset instead of the 10 that were in the text fixtures before.

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[LysandreJik]

Great, LGTM! Thank you for adding everything to a dataset.