Future waring in spec.py parser for numpy.vstack

[KennethNielsen]

When running the tests, the following warning appears:

  /home/kenneth/venv/PyExpLabSys/PyExpLabSys/file_parsers/specs.py:507: FutureWarning: arrays to stack must be passed as a "sequence" type such as list or tuple. Support for non-sequence iterables such as generators is deprecated as of NumPy 1.16 and will raise an error in the future.
    vstack = np.vstack(self.iter_scans)

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html

[KennethNielsen]

I think it should be simple enough to fix, most likely changing the line to:

vstack = np.vstack(list(self.iter_scans))

but I'd rather not do it without the ability to test it live.