Make enum casting case-insensitive

    typename std::enable_if_t<std::is_enum<T>::value, T> from_string_impl(std::string str, type_tag<T>) {

        str = from_string_impl(str, type_tag<std::string>());

        std::transform(str.begin(), str.end(), str.begin(), ::toupper);

        auto val = magic_enum::enum_cast<T>(str);

        auto val = magic_enum::enum_cast<T>(str, magic_enum::case_insensitive);

        if(val.has_value()) {

            return val.value();

        }