TP5.1使用composer安装验证码库的时候报错怎么解决，急求

原来使用TP的时候已经是两年前的事了，听说TP版本已经到了5+了，我自己也想做个小博客，所以使用了TP，但是在使用TP5.1的时候，安装TP的验证码库的时候，报错了，都找不到解决方法，搜索了网上也没有解决我的问题，具体的报错信息如下：

# composer require topthink/think-captcha
Using version ^3.0 for topthink/think-captcha
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for topthink/think-captcha ^3.0 -> satisfiable by
topthink/think-captcha[v3.0.0].
    - topthink/think-captcha v3.0.0 requires topthink/framework ^6.0.0 -> sat
isfiable by topthink/framework[6.0.x-dev, v6.0.0-rc2] but these conflict with
 your requirements or minimum-stability.