composer 创建项目错误

 Problem 1
    - league/flysystem[1.1.0, ..., 1.1.10] require ext-fileinfo * -> it is missing from your system. Install or enable PHP's fileinfo extension.
    - topthink/think-filesystem[v1.0.0, ..., v1.0.1] require league/flysystem ^1.1.4 -> satisfiable by league/flysystem[1.1.4, ..., 1.1.10].
    - Root composer.json requires topthink/think-filesystem ^1.0 -> satisfiable by topthink/think-filesystem[v1.0.0, v1.0.1].

解决方法：
出现此错误的原因是php.ini中的fileinfo扩展没有开启，开启 extension=fileinfo，再重新执行命令安装就可以了。