Bugfix schema file missing on install

[georgemccabe]

Change Summary

• Replaces deprecated setup.py with pyproject.toml configurations to pip install METdataio packages (METdbLoad, METreformat, and METreadnc).
• Added schema file to package data so it is available upon install
• Fix pip-audit GitHub Actions issues by reverting back to ubuntu 22.04 because ubuntu-latest now points to 24.04 and there are issues with the install on this OS

Pull Request Testing

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Pull Request Checklist

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