Documentation fix for depreciated keras.preprocessing

[AdityaPunetha]

Code still used the depreciated tf.keras.preprocessing.image method in usage documentation which caused other docs to show wrong documentation as well such as the Tensorflow's img_to_array

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[AdityaPunetha]

Changed indentation to multiple of 4 in line 2095 of confusion_matrix_test.py

[AdityaPunetha]

formatted confusion_matrix_test.py with black --line-length 80 as mentioned in format.sh

[fchollet]

This branch cannot be rebased due to conflicts

Please fix.

[fchollet]

Lint / Check the code format (pull_request) Failing after 2m — Check the code format

Please fix. You can simply run black on the file.

[fchollet]

This branch cannot be rebased due to conflicts

Please rebase.

[gbaned]

@AdityaPunetha Can you please check @fchollet's comments and keep us posted ? Thank you!

[gbaned]

@AdityaPunetha Any update on this PR? Please. Thank you!

[fchollet]

It appears this has already been fixed at head. Thanks anyway!