Clean POSYDON repository

[maxbriel]

This pull request:

• Updates the setuptools we use.
• Moves from versioneer.py to setuptools-scm for easier intergration.
• Automatically updates the conda.yaml version.
• Moves project definitions and requirements into pyproject.toml instead of defining them inside setup.py.
• Cleans up test CI by adding project parameters to pyproject.toml.