v0.4.2

• Switch to GitHub Actions for CI (instead of Travis CI)
• Various documentation and readme tweaks
• Add type annotations (#12, #13, by @KOLANICH)
• Introduce code formatting tools; black, isort, pre-commit
• Eliminate pkg_resources dependency and switch to importlib.resources for Python 3.12+ compatibility (#19)
• Switch to pyproject.toml based project metadata (#21)