Update ruby/setup-ruby action to v1.281.0

Author: renovate[bot]

.github/workflows/ci.yml

@@ -9,7 +9,7 @@ jobs:
     name: Ruby ${{ matrix.ruby }} CI
     steps:
       - uses: actions/checkout@93cb6efe18208431cddfb8368fd83d5badbf9bfd # v5.0.1
-      - uses: ruby/setup-ruby@v1
+      - uses: ruby/setup-ruby@675dd7ba1b06c8786a1480d89c384f5620a42647 # v1.281.0
         with:
           ruby-version: ${{ matrix.ruby }}
       - run: bundle install