List the test dependencies in pyproject.toml?

[nvaytet]

In Scipp, we list the test dependencies in the pyproject.toml.

Should we do the same for all packages?

This would allow us to do pip install esssans[test] which would give you an env where you can right away run the unit tests?
So for a local editable build you could do pip install -e .[test] (I think?).

This would also mean that we could get the test dependencies in the conda recipe from the pyproject file, as we do for the run dependencies?