Move black and isort settings to pyproject

[Sriganesh-k]

• pyproject.toml now stores the Black/isort settings.
• .pre-commit-config.yaml still runs Black and isort, but no longer repeats their options.
• Pre-commit automatically reads the settings from pyproject.toml.

[JohannesWeinbrecht]

LGTM

[Sriganesh-k]

Updated — both pre-commit hooks now explicitly use pyproject.toml (--settings-path for isort and --config for Black), and I tested both locally