The necessary changes to produce valid OpenAPI docs are now in
the latest release of LabThings. This change updates it.
Also, isort was trying to sort my virtual environment, hence
the change to pyproject.toml.
I don't know why that happened - maybe an update to isort?
More or less everything is now done by setup.py
Pipfile simply installs the module in editable mode, which
recursively resolves dependencies as defined in setup.py.