Update source style to match current settings from black

[yt-ms]

Problem description

From a clean checkout, running make qa reformats a bunch of files, presumably because the version of Black has moved on.

Code Sample

E.g. in test_workspace_io.py:

@pytest.mark.parametrize(
    "example, filename", [("getting_started", "GettingStarted.json"),],
)

becomes

@pytest.mark.parametrize(
    "example, filename",
    [
        ("getting_started", "GettingStarted.json"),
    ],
)

Context

``` System Information ================== OS Windows OS-release 10 Python 3.7.5 Package Versions ================ depinfo 1.5.4 httpx 0.15.3 ordered-set 3.1 pip 20.2.3 pydantic 1.6.1 python-dotenv 0.14.0 setuptools 41.2.0 structurizr-python 0+unknown ```

[Midnighter]

I've pushed a commit that introduces all those style changes. You probably will have to rebase #25

[yt-ms]

Thanks!