Description of proposed changes

The first step to address #1836.

Also xref #695.

References:

• https://peps.python.org/pep-0517/
• https://peps.python.org/pep-0518/
• https://setuptools.pypa.io/en/latest/userguide/quickstart.html#basic-use
• https://github.com/pypa/setuptools_scm/#pyprojecttoml-usage

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If wrapping a new module, open a 'Wrap new GMT module' issue and submit reasonably-sized PRs.
• If adding new functionality, add an example to docstrings or tutorials.

Slash Commands

You can write slash commands (/command) in the first line of a comment to perform
specific operations. Supported slash commands are:

• /format: automatically format and lint the code
• /test-gmt-dev: run full tests on the latest GMT development version