Mock is broken in subprocesses on Mac OS

[yuyuyureka]

https://stackoverflow.com/questions/70425526/mocking-methods-called-within-multiprocessing-doesnt-work-on-mac

On Linux, the default start method is fork, while on MacOS and Windows it is spawn.

So the netbox tests break with the usage of multiprocessing.Pool in cosmo/clients/netbox_v4.py.