Bump ruby/setup-ruby from 1.215.0 to 1.221.0 (#1741)

Bumps [ruby/setup-ruby](https://github.com/ruby/setup-ruby) from 1.215.0 to 1.221.0.
- [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...32110d4)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/exercise-tests.yml

@@ -22,7 +22,7 @@ jobs:
       - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
 
       - name: Set up Ruby
-        uses: ruby/setup-ruby@2654679fe7f7c29875c669398a8ec0791b8a64a1
+        uses: ruby/setup-ruby@32110d4e311bd8996b2a82bf2a43b714ccc91777
         with:
           ruby-version: ${{ matrix.ruby-version }}
           bundler-cache: true