Bump ruby/setup-ruby from 1.215.0 to 1.218.0

Bumps [ruby/setup-ruby](https://github.com/ruby/setup-ruby) from 1.215.0 to 1.218.0.
- [Release notes](https://github.com/ruby/setup-ruby/releases)
- [Changelog](https://github.com/ruby/setup-ruby/blob/master/release.rb)
- [Commits](ruby/setup-ruby@2654679...d781c1b)

---
updated-dependencies:
- dependency-name: ruby/setup-ruby
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/ruby.yml

@@ -34,7 +34,7 @@ jobs:
     # To automatically get bug fixes and new Ruby versions for ruby/setup-ruby,
     # change this to (see https://github.com/ruby/setup-ruby#versioning):
     # uses: ruby/setup-ruby@v1
-      uses: ruby/setup-ruby@2654679fe7f7c29875c669398a8ec0791b8a64a1 # v1.215.0
+      uses: ruby/setup-ruby@d781c1b4ed31764801bfae177617bb0446f5ef8d # v1.218.0
       with:
         ruby-version: ${{ matrix.ruby-version }}
         bundler-cache: true # runs 'bundle install' and caches installed gems automatically