Cannot save AutoEncoder

Created by: kennysong

The official instructions say to use joblib for pickling PyOD models.

This fails for AutoEncoders, or any other TensorFlow-backed model as far as I can tell. The error is:

>>> dump(model, 'model.joblib')
...
TypeError: can't pickle _thread.RLock objects

Note that it's not sufficient to save the underlying Keras Sequential model, since I need the methods & variables of BaseDetector (like .decision_scores_ or .decision_function().