Martian 4.0.6

Feature improvements

• The way mrjob scans its child processes in order to track memory and I/O usage is now more efficient. It also polls more frequently when running with --monitor.
• On linux operating systems, mrjob is now set as a subreaper for its child processes, allowing it to collect rusage information when stage code launches child processes but fails to wait on them.
• The API backing the web UI will now set the Content-Type and other headers more accurately for most metadata files.
• Minor bumps to dependencies.

Bug fixes

• Correctly handle reattaching to a pipestance via _mrosource.
• Catch and report import errors for the stage code in the python adapter.
• Fix a error in the VSCode extension which prevented formatting from working when there was no workspace defined.