v1.0.3 Release

Bump dependency TensorFlow version to 2.2.0.
User now can use custom metrics and loss.
User now can specify the tuner to use for Task APIs like ImageClassifier.
Use Keras preprocessing layers for ImageAugmentation.
If not epochs is not specified, and validation_data is not provided,
it will use the best models best number of epochs for retraining the best model with the entire training set.
Bug fixes:
All bugs in the tutorials are fixed.
All the tutorials can run smoothly.
Breaking changes:
ImageAugmentation args updated.