Add scripts section to cutter-py project

[yannickperrenet]

Idea:

• https://medium.com/octopus-wealth/python-scripts-26e3d0bd5277
• https://stackoverflow.com/questions/59286983/how-to-run-a-script-using-pyproject-toml-settings-and-poetry
• https://github.com/python-poetry/poetry-core/pull/40

For example, in pyproject.toml of https://github.com/yannickperrenet/cutter-py:

[tool.poetry.scripts]
format = "scripts:format"
lint = "scripts:lint"