解决curl error 28 while downloading https://repo.packagist.org/packages.json: Timeout was reac head

下载 https://repo.packagist.org/packages.json 时出现 curl 错误 28：Timeout was reac head，超时问题，解决方案跟npm一样，要么开代理（有时候开也不好用），要么换国内镜像。

composer 更改为国内镜像源（我这里选的阿里源）：

composer config -g repo.packagist composer https://mirrors.aliyun.com/composer/

然后再下载就好了