Composer 安装TP 6 ([Composer\Downloader\TransportException] Content-Length mismatch, receive)

环境：php 7.3.4 + mysql 8.0.12

1.安装Composer好后，进入网页根目录

composer create-project topthink/think tp

2.安装TP6出现错误：

[Composer\Downloader\TransportException]
Content-Length mismatch, received 70336 bytes out of the expected 1007047

原因是SSL证书的问题，解决办法：

3.下载php_ssh2.dll、php_ssh2.pdb,http://windows.php.net/downloads/pecl/releases/ssh2/0.12/

复制到D:\phpstudy_pro\Extensions\php\php7.3.4nts\ext下

4.重启nginx,php

解决