chore: Migrate from setup.py to pyproject.toml - #4478

It'd probably be ideal to have #4344 done before merging this, yeah?

@tokoko clarification,I have one task on my to-do list related to this conversation-> #4380 (comment) do you think it's still valid after this PR change. Thanks

@redhatHameed yup, that's still valid. this PR only changes where requirements are defined, nothing else.

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