[R4R] Add rb-ruby-enum

[sodre]

ref: #9315

Checklist

• License file is packaged (see here for an example)
• Source is from official source
• Package does not vend other packages
• Build number is 0
• A tarball (url) rather than a repo (e.g. git_url) is used in your
  recipe (see
  here
  for more details)
• GitHub users listed in the maintainer section have posted a comment confirming they are willing to be listed there

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipes/rb-ruby-enum) and found it was in an excellent condition.

[sodre]

@conda-forge/staged-recipes the rb-ruby-enum recipe is ready for review/merge

[beckermr]

We should add a ruby specific github group for conda-forge so that they can be pinged directly. I don't have enough expertise to review this one.

[isuruf]

We should add a ruby specific github group for conda-forge so that they can be pinged directly

That'll just be @sodre. 😄