swap out `setup.py` for `pyproject.toml`

[jGaboardi]

Following the merge of #199, we'll want to modernize the installation infrastructure.

xref:

• https://github.com/pysal/pointpats/pull/117
• https://github.com/pysal/mapclassify/pull/193
• etc.

@weikang9009 Does this sound OK to you?

• [x] black repo – #201
• [x] ruff repo – #202
• [x] pre-commit for formatting and linting – #202
• [x] setup tool_scm for versioning – #203
• [x] prune files – #203
• [x] etc.