Ruby 3.4 frozen string issue

Would you accept a PR to fix the frozen string issue in ruby 3.4?

```
gems/hosts-0.1.1/lib/aef/hosts/element.rb:76: warning: literal string will be frozen in the future (run with --debug-frozen-string-literal for more information)
```

See https://blog.saeloun.com/2024/05/20/frozen-string-literal/