Modernize

[dyollb]

move metadata from setup.py to pyproject.toml

• package version is dynamically extracted from nrrd.__version__

upgrade pre-commit hooks

• replace flake8 hook by https://github.com/PyCQA/flake8, which is "standard" (running the old hook was asking me for a gitlab password)
• add typos hook (only found one typo, but doesn't cost much to run it)

[addisonElliott]

This looks great, thanks! One minor comment about adding link to docs.