当我运行时，composer update我收到此错误消息：

Loading composer repositories with package information
Updating dependencies (including require-dev)
    Failed to download psr/log from dist: The zip extension and unzip command are both missing, skipping.
The php.ini used by your command-line PHP is: /etc/php/7.0/cli/php.ini
    Now trying to download from source

我需要做什么才能启用 zip 和 unzip 命令，以便作曲家可以下载依赖项？