Make use of pyproject-fmt

[funkyfuture]

once it stops to re-order seemingly randomly, possibly with the latest release from today, pyproject-fmt should be used like black for applying a canonical formatting and verifying it (maybe there's also a flake8 plugin for that?).

due to its extrapolation of trove classifiers about supported language versions, it fits well in conjunction with hynek's GH Action for building and validating wheels.

[funkyfuture]

all the [tool.*] tables are now kept in order and this tool is now a requirement for the inclusion of https://github.com/hynek/build-and-inspect-python-package in the pipelines of this project.

[funkyfuture]

i haven't tested intermediate versions, but the current release reorders tables unpleasantly: tox-dev/toml-fmt#3

to clarify: this tool would be a requirement for baipp to provide inferred, up-to-date Pyton compatibility trove classifiers.