Need for recent versions of Ruby, specified

after dealing with the problem in #18, I got this error:

```
ruby_dep-1.5.0 requires ruby version >= 2.2.5, ~> 2.2, which is incompatible with the current version, ruby 3.1.2p20
```

2 problems here.

1. Ruby 2.2 is ANCIENT and unsupported. The current stable version is 3.1, and nothing before 2.7 is supported.
2. There's no version of Ruby specified in the repo. It's normal to have a `.ruby-version` file which specifies the version of Ruby that the project was created with.

首先检查仓库的 Ruby 和依赖配置，然后确定 Ruby 版本在哪里声明，或者是否缺失。更新项目以使用受支持的 Ruby 版本，添加所请求的 .ruby-version 文件，并验证依赖错误不再发生。

由索引模型根据 Issue 内容生成。