安装tp6时出现Composer 版本问题：

Warning from https://repo.packagist.org: Support for Composer 1 is deprecated and some packages will not be available. You should upgrade to Composer 2. See https://blog.packagist.com/deprecating-composer-1-support/

问　　题：Composer 版本过低

解决方式：升级

升级方式：composer selfupdate

查看当前版本

回滚到安装的上一个版本

composer self-update -r

更新到指定版本

composer self-update 1.10.8

版本更新并删除旧版本的备份

composer self-update --clean-backups

Composer 版本