Switch project to use pyproject.toml

[hagenw]

This modernizes the Python infrastructure of the project:

• Replace setup.cfg by pyproject.toml and update setup.py to focus only on dynamic package data selection
• Replace PEP8 checking in pre-commit with flake8 by ruff
• Add checking for common spelling errors with codespell in pre-commit

[codecov]

Codecov Report

Merging #92 (52dfa8d) into main (dfc83d6) will not change coverage.
The diff coverage is 100.0%.

Files	Coverage Δ
opensmile/__init__.py	100.0% <100.0%> (ø)
opensmile/core/define.py	100.0% <ø> (ø)
opensmile/core/lib.py	100.0% <100.0%> (ø)
opensmile/core/smile.py	100.0% <100.0%> (ø)