External dependency import failing in DiffusionQC Python test

I’ve noticed that the DiffusionQC extension module’s test has been failing for a while:

also mentioned in:
Fix import errors by lassoan · Pull Request #47 · pnlbwh/SlicerDiffusionQC · GitHub

And this happens despite plumbum being specified in the setup.py in the install_requires dependencies:

I’ve also seen that @jcfr did a PR a long time ago:
Pull requests · pnlbwh/SlicerDiffusionQC · GitHub

I haven’t got merge rights, so I cannot do much about it. It’d probably address the config issues of the module, but the test issue is probably unrelated.

So concerning the test, is there something that the extension Python code is missing?