WIP: Move to setuptools_scm for version generation.

[mithro]

Convert the library to use setuptools_scm module rather than my own hacky script.

TODO Items;

• [ ] Improve the version file that is being generated.
• [ ] Figure out how to correctly specify dependencies -- should it be pyproject.toml, setup.cfg, setup.py or something else?
• [ ] Check the version numbers are the same as before.