我尝试使用Mac OS在我的电脑上安装compose 在终端上，我输入了命令“composer update”，它会发生错误。
Loading composer repositories with package information
Initializing PEAR repository https://pear.php.net
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.
Problem 1
- Installation request for magento/product-community-edition 2.1.5 -> satisfiable by magento/product-community-edition[2.1.5].
- magento/product-community-edition 2.1.5 requires zendframework/zend-stdlib ~2.4.6 -> satisfiable by zendframework/zend-stdlib[2.4.10, 2.4.11,2.4.12, 2.4.13, 2.4.6, 2.4.7, 2.4.8, 2.4.9] but these conflict with your requirements or minimum-stability.