Major Features and Improvements
* Added a tf.Example <-> Arrow coder.
* Added a tf.Example -> `Dict[str, np.ndarray]` coder (this is a legacy format
used by some TFX components).
* Added some common Arrow utilities (`tfx_bsl.arrow.array_util`).
* Added a python class, `tfx_bsl.beam.Shared` that helps sharing a single
instance of object across multiple threads.
* Added dependency on `apache-beam[gcp]>=2.16,<3`.
* Added dependency on `tensorflow-metadata>=0.15,<0.16`.
Bug Fixes and Other Changes
Breaking Changes
Deprecations