Migrate from setup.py to pyproject.toml based build

[sdhiscocks]

Pip (and other tools) now consider setup.py legacy, and such should migrate to pyproject.toml (and associated setup.cfg for setuptools).

This also removes dependency on setuptools_scm_git_archive as this is now integrated into setuptools_scm >= 7.

[codecov[bot]]

Codecov Report

Base: 94.62% // Head: 94.62% // No change to project coverage :thumbsup:

Coverage data is based on head (4519edf) compared to base (5276c1b). Patch has no changes to coverable lines.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #708 +/- ## ======================================= Coverage 94.62% 94.62% ======================================= Files 172 172 Lines 8845 8845 Branches 1714 1714 ======================================= Hits 8370 8370 Misses 343 343 Partials 132 132 ``` | Flag | Coverage Δ | | |---|---|---| | integration | `70.35% <ø> (-0.03%)` | :arrow_down: | | unittests | `90.79% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dstl#carryforward-flags-in-the-pull-request-comment) to find out more. Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dstl). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=dstl)

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