AttributeError: Can't pickle local object 'NestedPool.Process.<locals>.NoDaemonProcess' on Mac

[anilbey]

This issue is raised on macos.

Here's how to reproduce it on github actions (#250).

https://github.com/BlueBrain/BluePyMM/runs/7941237020?check_suite_focus=true