Enable building with modern Ruby versions

[skipkayhil]

Update Bundler version for Ruby 3.2

Previously, Bundler would use version 1.14.6 specified in the
Gemfile.lock. However, this version of Bundler uses the #untaint method
which was removed in Ruby 3.2.

To fix this, the locked version of Bundler has been updated. The version
chosen is the last 2.3.x release as 2.4 drops support for Rubyies 2.3 -
2.5. If dropping support for EoL Rubies is not an issue then the Bundler
version could be upgraded further.

---

Replace #exists? with #exist?

The #exists? method has been deprecated since Ruby 2.1.0 and was finally
removed in Ruby 3.0

[skipkayhil]

@tinted-theming anything I can do to move this forward?

[skipkayhil]

@belak @JamyGolden @obahareth hey all, happy to help maintain this repo if there's interest. I'd really love to be able to keep using this builder and I recognize everyone's time can be spread pretty thinly across projects

[JamyGolden]

Hey @skipkayhil. I didn't get a notification when you created this in Jan 😞

Currently the builder that supports the latest builder spec is base16-builder-go and the binaries are provided on the repo too. We'd be happy to have you on board and working on something in the project! If you specifically want to work on this ruby builder (even though we have an up to date builder), then go for it! I can add you as a maintainer to the repo. If you want to be involved in other things (you could do both too), then let me know!

[belak]

This looks good to me, though I don't know ruby very well - if you want to update and maintain the Ruby builder, we'd love to have your help!

[skipkayhil]

That would be awesome! Don't want to go too crazy with changes but I would love to package this as a gem so that it could be easily installed/run without having to clone the repo

[JamyGolden]

Great! I've sent an maintainer invite for this repository @skipkayhil