Function is_boolean

extern/json/json.hpp:20531–20534

@brief return whether value is a boolean @sa https://json.nlohmann.me/api/basic_json/is_boolean/

    /// @brief return whether value is a boolean
    /// @sa https://json.nlohmann.me/api/basic_json/is_boolean/
    constexpr bool is_boolean() const noexcept
    {
        return m_type == value_t::boolean;
    }

    /// @brief return whether value is a number
    /// @sa https://json.nlohmann.me/api/basic_json/is_number/