Composer报错提示：
Your requirements could not be resolved to an installable set of packages.
Problem 1
- hyperf/validation v2.0.9 requires hyperf/command ~2.0.0 -> satisfiable by hyperf/command[2.0.x-dev, v2.0.0, v2.0.10, v2.0.3, v2.0.5, v2.0.9] but these conflict with your requirements or minimum-stability.
- Installation request for hyperf/validation ^2.0 -> satisfiable by hyperf/validation[v2.0.0, v2.0.3, v2.0.5, v2.0.8, v2.0.9].
Installation failed, reverting ./composer.json to its original content.
解决方法：
执行composer update hyperf/command