fix: ruby 버전 3.0.6으로 업데이트

Author: rha6780

.github/workflows/jekyll.yml

@@ -36,7 +36,7 @@ jobs:
       - name: Setup Ruby
         uses: ruby/setup-ruby@v1 # v1.195.0
         with:
-          ruby-version: "2.7.2" # Not needed with a .ruby-version file
+          ruby-version: "3.0.6" # Not needed with a .ruby-version file
           bundler-cache: true # runs 'bundle install' and caches installed gems automatically
           cache-version: 0 # Increment this number if you need to re-download cached gems
       - name: Setup Pages