Use pyproject.toml, remove requirements.txt

[sneakers-the-rat]

keeping consistent with the content of our guides, removed the requirements.txt and switched to using pyproject.toml. They had already gotten out of sync, and so one lil tiny tweak to hopefully make things a lil smoother.

Set it to use dynamic versioning bc that's what i saw u using over here pyOpenSci/pyosMeta#85

and bypassed package check since this isn't a package per se.

dependencies are made not optional since it's not clear what one would be doing installing this empty package without the deps lol <3

[willingc]

Nice cleanup @sneakers-the-rat

[sneakers-the-rat]

Ah but I did not merge main here after the docs test PR was merged, so that will fail after removing requirements.txt, hang on and ill make another :)