v0.1.2

Added

• Add "standard user recipe" to documentation.
• Add unit tests using mock to simulate preemption.
• Logging to increase transparency around why checkpoints are kept vs. deleted.
• Expand on uses of restore_args in colab.
• Expose utils_test.
• Add msgpack_utils to move toward eliminating Flax dependency.
• CheckpointManager starts a background thread to finalize checkpoints so that
  checkpoints are finalized as soon as possible in async case.

Changed

• Remove CheckpointManager update API.
• Remove support for deprecated GDA.
• Add tmp suffix on step directory creation in CheckpointManager.save.

Fixed

• Preemption when using keep_time_interval caused the most recent steps before
  preemption to be kept, despite not falling on the keep time interval.