Bump ruby

Author: tannewt

.github/workflows/htmlproofer.yml

@@ -10,7 +10,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
         with:
-          ruby-version: '2.6'
+          ruby-version: '3.3'
       - uses: actions/cache@v4
         with:
           path: vendor/bundle