Bump ruby/setup-ruby from 1.202.0 to 1.203.0

Bumps [ruby/setup-ruby](https://github.com/ruby/setup-ruby) from 1.202.0 to 1.203.0.
- [Release notes](https://github.com/ruby/setup-ruby/releases)
- [Changelog](https://github.com/ruby/setup-ruby/blob/master/release.rb)
- [Commits](ruby/setup-ruby@a2bbe5b...2a18b06)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/gh-pages.yml

@@ -28,7 +28,7 @@ jobs:
         with:
           fetch-depth: 0 # need full history to get page last modified times
       - name: Setup Ruby
-        uses: ruby/setup-ruby@a2bbe5b1b236842c1cb7dd11e8e3b51e0a616acc # v1.202.0
+        uses: ruby/setup-ruby@2a18b06812b0e15bb916e1df298d3e740422c47e # v1.203.0
         with:
           ruby-version: '3.1'
           bundler-cache: true # runs 'bundle install' and caches installed gems automatically