Update Gemfile to specify github-pages version and change Ruby version in GitHub Actions workflow

- Updated the github-pages gem version to '~> 227' for compatibility.
- Changed the Ruby version in the GitHub Actions workflow from 2.7 to 3.0 for improved support.

.github/workflows/deploy.yml

@@ -24,7 +24,7 @@ jobs:
       - name: Setup Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '2.7'
+          ruby-version: '3.0'
           bundler-cache: false
           
       - name: Install dependencies

Gemfile

@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 
 # GitHub Pages compatible gems
-gem 'github-pages', group: :jekyll_plugins
+gem 'github-pages', '~> 227', group: :jekyll_plugins
 gem 'jekyll-feed', '~> 0.12'
 gem 'jekyll-sitemap'
 gem 'jekyll-seo-tag'