Restrict `radix` usage to its base module so that it doesn't affect Ruby's `String.b`

Hi,

Great work with `spider-gazelle`! I'm trying it out and it already feels amazing!

Here's a simple patch to restrict `radix` usage to its base module so that it doesn't affect Ruby's `String.b`.

Spider-Gazelle's usage of radix doesn't need the whole gem required and the current approach is an issue with at least [MRI's ERB](https://github.com/ruby/ruby/blob/trunk/lib/erb.rb#L600).


BTW, quick question, how far are you planning on taking this implementation? Are you already using it in production somewhere?

Thanks,
Darío