`pyproject.toml`: specify dependencies dynamically with `setuptool`

Something we might try after this PR: you can specify the dependencies dynamically with newer `setuptool`. I didn't include it since I wasn't sure how it would interact with PySold's current setuptools version pinning

https://github.com/opera-adt/dolphin/blob/main/pyproject.toml#L23-L34

_Originally posted by @scottstanie in https://github.com/insarlab/PySolid/pull/69#discussion_r1295805458_
            