Upgrade CI lint step from Ruby 3 to 4 (#1673)

Author: larouxn

.github/workflows/ci.yml

@@ -24,10 +24,10 @@ jobs:
     steps:
       - uses: actions/checkout@v6
 
-      - name: Setup Ruby 3.x
+      - name: Setup Ruby 4.x
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3
+          ruby-version: 4
           bundler-cache: true
 
       - name: Rubocop