python setup.py gives deprecation warnings

[seisman]

In our CI workflow, we run commands like python setup.py sdist --formats=zip to build source or binary distributions. The command gives the following deprecation warnings:

SetuptoolsDeprecationWarning: setuptools.installer is deprecated. Requirements should be satisfied by a PEP 517 installer.

It seems python setup.py is no longer recommended to build distributions.

Reference: https://blog.ganssle.io/articles/2021/10/setup-py-deprecated.html#summary

[weiji14]

So reading into that blog post, it looks like we'll need to

1. Have make package do python -m build

Specifically, modify the line here:

pygmt/Makefile

Lines 31 to 32 in ba51f80

	package:
	python setup.py sdist bdist_wheel

And then, we'll need to add build as a dependency in the publish-to-pypi.yml workflow here:

pygmt/.github/workflows/publish-to-pypi.yml

Lines 36 to 37 in ba51f80

	- name: Install dependencies
	run: python -m pip install setuptools wheel

Now the above is the minimum we can do. If we want to go for hard mode, it sounds like we can

2. Put everything in pyproject.toml somehow

I.e. remove setup.py, setup.cfg and all those crazy files in the top level directory. So a bit like #1055, but using 'native' pypa tools instead of poetry. But that will require a bit more reading into all those PEPs.

I'd recommend doing 1) for a PyGMT v0.6.1, and maybe save 2) for PyGMT v0.7.0