Update Ruby version to 3.4 in CI workflow

Bumps the Ruby version from 3.3 to 3.4 in the GitHub Actions CI configuration for both Jekyll and Rails jobs to ensure compatibility with the latest Ruby release.

Author: toshimaru

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3.3
+          ruby-version: 3.4
           bundler-cache: true
       - name: Jekyll Build
         run: bundle exec jekyll build
@@ -40,7 +40,7 @@ jobs:
         run: cd rails && git fetch --depth=1 origin refs/tags/v8*:refs/tags/v8*
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3.3
+          ruby-version: 3.4
           bundler-cache: true
       - name: Doc Build
         run: rake build