Move to rye, add testing for py312

[trappitsch]

• [x] Move project over to Rye for management and update / clean files
• [x] Update workflows for testing and publishing
• [x] Add py3.12 for testing, use 3.12 for publishing
• [x] Update contributor documentation
• [x] Get xdoctest to run and pass

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 100.00%. Comparing base (01cfda3) to head (e07791a). Report is 1 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #109 +/- ## ========================================= Coverage 100.00% 100.00% ========================================= Files 23 23 Lines 1464 1456 -8 ========================================= - Hits 1464 1456 -8 ``` | [Flag](https://app.codecov.io/gh/galactic-forensics/iniabu/pull/109/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=galactic-forensics) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/galactic-forensics/iniabu/pull/109/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=galactic-forensics) | `?` | | 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=galactic-forensics#carryforward-flags-in-the-pull-request-comment) to find out more.

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[trappitsch]

There is some pytest weirdness going on, most likely with initialization. For example, in the isotope doctest, it seems to not initialize iniabu properly again but use the nist database. needs to be double checked

[trappitsch]

Doctest on py3.8 fails. These are minor differences that come from the numpy > 2 for py39+. Ignoring these failures, as tests actually do pass.

[trappitsch]

Drop support for python 3.8 (it is almost EOL and there are no new features coming for now, so the current 1.2.1 version works just fine on 3.8. This avoids the whole numpy headache