ci: update ruby version to 3.4

Ruby 3.1 and 3.2 are now EOL
See: https://www.ruby-lang.org/en/downloads/branches/

.github/workflows/cd.yml

@@ -18,7 +18,7 @@ jobs:
 
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3.3
+          ruby-version: 3.4
           bundler-cache: true
 
       - uses: actions/setup-node@v6

.github/workflows/ci.yml

@@ -27,7 +27,7 @@ jobs:
 
     strategy:
       matrix:
-        ruby: ["3.1", "3.2", "3.3"]
+        ruby: ["3.3", "3.4"]
 
     steps:
       - name: Checkout

.github/workflows/starter/pages-deploy.yml

@@ -42,7 +42,7 @@ jobs:
       - name: Setup Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3.3
+          ruby-version: 3.4
           bundler-cache: true
 
       - name: Build site