Function const_iterator lower_bound

src/toml.hpp:7905–7909

		}

		TOML_PURE_GETTER
		const_iterator lower_bound(std::string_view key) const noexcept
		{
			return const_iterator{ const_cast<table&>(*this).get_lower_bound(key) };
		}

#if TOML_ENABLE_WINDOWS_COMPAT