安装tp6.0 Could not find package topthink/think with stability stable.

操作步骤：

1. git bash到要安装的地方

2. 执行命令： composer create-project topthink/think tp6

出现的错误：

[InvalidArgumentException]

Could not find package topthink/think with stability stable.

解决方案：

删除之前的镜像：composer config -g --unset repos.packagist