ci: Bump ruby version for generate-docs to 3.4

Author: kspurgin

.github/workflows/generate-docs.yml

@@ -13,7 +13,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "3.1"
+          ruby-version: "3.4"
       - name: Install yard
         run: gem install yard --no-document
       - name: Install kramdown