poetry section for development deps in pyproject.toml is out-of-date

[xmnlab]

we need to update the section for development dependencies used by poetry in the pyproject.toml file.

ref: https://github.com/osl-incubator/scicookie/blob/main/src/scicookie/%7B%7Bcookiecutter.project_slug%7D%7D/build-system/poetry-pyproject.toml#L39

current section:

[tool.poetry.dev-dependencies]

should be changed to:

[tool.poetry.group.dev.dependencies]