v4.0.13

This release includes minor bug fixes and improvements

Bug fixes

• When run with --zip, do not remove non-empty metadata directories.

Python adapter

• Handle conversion of pathlib.Path objects to strings when
  serializing outputs.
• Add martian.clear() as a convenience method to set all output
  parameters to null.

Documentation

• Fix some typos in python docstrings.
• Improve comments in parts of the go code.
• Add a note in the slurm template about issues with VSizeFactor.

Logging and error messages

• Improve the error message for "not queued or running" in cluster mode,
  to clarify the difference between a job that started but then terminated
  unexpectedly without reporting an error vs. a job which never started up at all.
• Auto-retry on slurm socket timeout error messages.
• Correctly detect and report memory limits imposed with cgroup v2 as well
  as cgroup v1.