Dev-cmd

Add support for parallelizing execution of commands in an task.

Fix project root dir detection.

Guarantee commands are run in the root project dir or else the custom
`cwd` project sub-dir defined for the command.

Update project metadata.

$ git push --tags https://github.com/jsirois/dev-cmd HEAD:main


The release is automated and will create a PyPI release at
[https://pypi.org/project/dev-cmd/<version>/](https://pypi.org/project/dev-cmd/#history).