在vue2环境下，默认安装 npm install vue-i18n 的版本是 vue-i18n@9.2.2，所以报错信息如下：
PS D:\myFile\dev\YSJ-dev\cbj-mall-manage> npm i vue-i18n -save
npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR!
npm ERR! While resolving: vue-admin-template@4.4.0
npm ERR! Found: vue@2.6.10
npm ERR! node_modules/vue
npm ERR! vue@"2.6.10" from the root project
npm ERR!
npm ERR! Could not resolve dependency:
npm ERR! peer vue@"^3.0.0" from vue-i18n@9.2.2
npm ERR! node_modules/vue-i18n
npm ERR! vue-i18n@"*" from the root project
npm ERR!
npm ERR! Fix the upstream dependency conflict, or retry
npm ERR! this command with --force, or --legacy-peer-deps
npm ERR! to accept an incorrect (and potentially broken) dependency resolution.
npm ERR!
npm ERR! See C:\Users\Administrator\AppData\Local\npm-cache\eresolve-report.txt for a full report.
npm ERR! peer vue@"^3.0.0" from vue-i18n@9.2.2 （意思是版本不匹配）
npm view vue-i18n versions --json 命令查看所有的版本
选择安装合适的版本即可
后面我 使用的是5.0.0 npm install vue-i18n@5
