Bump ruby version from 2.7 to 3.1.

Author: tompollard

.github/workflows/website.yml

@@ -19,7 +19,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '2.7'
+          ruby-version: '3.1'
           bundler-cache: true
 
       - name: Set up Python