Previously we relied on the toml package for parsing TOML configuration files. However, this package is no longer considered the best provider of such support and is actually now deprecated by some Linux distros. Further, TOML has made its way into the Python standard library (for Python 3.11+, tomllib Therefore it was best to migrate to no dependency at all for Python 3.11+ or use tomli otherwise. For write capabilities we've added tomli-w. Many application have no need to write TOML, so this is an optional dependency.
Proper support for package extras is now provided. To explicitly enable TOML, developers can specify cmdkit[toml] as a dependency.