Suppress Ruby warning: `&' interpreted as argument prefix

Hey @jlindsey, another quick one: when running a Ruby syntax check against the `version.rb` file, it was issuing the following warning...

```
version.rb:19: warning: `&' interpreted as argument prefix
```

_(FYI, I used: `ruby -W7 -c core_ext.rb` to run the syntax check)_

Thanks!