Python API 0.6.0

Feature

• model.to_jax_function now always outputs a FeatureEncoder to help feeding
  data to the JAX model.
• The default value of num_candidate_attributes in the CART learner is
  changed from 0 (Random Forest style sampling) to -1 (no sampling). This is
  the generally accepted logic of CART.
• model.to_tensorflow_saved_model support preprocessing functions which have
  a different signature than the YDF model.
• Improve error messages when feeding wrong size Numpy arrays.
• Add option for weighted evaluation in model.evaluate.

Fix

• Fix display of confusion matrix with floating point weights.

Known issues

• MacOS build is broken.