ci: use ruby version from .ruby-version to match gem requirements

Author: nevalsar

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

@@ -35,7 +35,6 @@ jobs:
       - name: Setup Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '3.0' # 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