Maintenance Updates

[davidlday]

• [x] convert README to markdown
• [x] bring packaging to current practices
  • [x] create pyproject.toml
  • [x] move settings to setup.cfg
• [x] retire Codacy in favor of GitHub Actions (pylint, black)
  • [x] add lint job to CI workflow
• [x] use pypi-publish
  • [x] create test publish workflow on tags
  • [x] update publish on release reworkflow
• [x] add twine check job to CI workflow

[davidlday]

Closed by #22