[feature] Update to the config file feature

Results differ based on type when parsing a std::optional<T> with default_value std::nullopt

Full migration to c++26 modules via a separate branch

Infinite recursion in CLI::App::get_option_no_throw

Help output is non-deterministic for needs and excludes

[v2.6.2] Error in documentation

Questions about MISRA static analysis

Since v2.5.0, there are trailing whitespaces in the help text. Output from the readme example:

Colorful help

Help for a fallthrough subcommands does not show upper subcommand help