Switch project to use pyproject.toml

[hagenw]

This modernizes the Python infrastructure of the project:

• Replace setup.py and setup.cfg by pyproject.toml
• Replace PEP8 checking in pre-commit with flake8 by ruff
• Add checking for common spelling errors with codespell in pre-commit

In addition, it exposes a few more methods to the documentation:

[codecov[bot]]

Codecov Report

Merging #83 (d948e47) into main (b97cc13) will not change coverage. The diff coverage is 100.0%.

Impacted Files	Coverage Δ
audobject/core/config.py	100.0% <ø> (ø)
audobject/core/dictionary.py	100.0% <ø> (ø)
audobject/core/resolver.py	100.0% <ø> (ø)
audobject/core/utils.py	100.0% <ø> (ø)
audobject/__init__.py	100.0% <100.0%> (ø)
audobject/core/api.py	100.0% <100.0%> (ø)
audobject/core/object.py	100.0% <100.0%> (ø)
audobject/core/parameter.py	100.0% <100.0%> (ø)
audobject/core/testing.py	100.0% <100.0%> (ø)
audobject/resolver/__init__.py	100.0% <100.0%> (ø)
... and 1 more