Should black be in setup.py optional deps for tests?

Maybe I'm missing something : shouldn't we add `black` to optional deps for `test` set of optional deps?

```
    "tests": [
        "pytest<8.0.0",
        "nbmake",
        "scipy",
        "imageio[pyav]",
        "jupyterlab",
        "jupyter-rfb>=0.4.1",
        "ipywidgets>=8.0.0,<9",
        "scikit-learn",
        "tqdm",
        "sidecar",
    ],
```