Upgrade Ruby to 3.3 and jekyll to 4.3

Follow up to ManageIQ/manageiq.org#1192

Author: Fryguy

.github/workflows/ci.yaml

@@ -15,7 +15,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '2.7'
+          ruby-version: '3.3'
           bundler-cache: true
         timeout-minutes: 30
       - name: Get manageiq.org repo

Gemfile

@@ -1,6 +1,6 @@
 source "https://rubygems.org"
 
-gem "jekyll"
+gem "jekyll", ">= 4.3.4"
 gem "jekyll-toc"
-gem "nokogiri", "~> 1.13", ">= 1.13.6" # dependency of jekyll-toc, listed to fix CVEs
+gem "nokogiri", "~> 1.17", ">= 1.17.2" # dependency of jekyll-toc, listed to fix CVEs
 gem "rake"