Update jekyll.yml to include code on setting up Node.

Author: muziejus

.github/workflows/jekyll.yml

@@ -33,6 +33,12 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+      - name: Setup Node
+        uses: actions/setup-node@v2
+        with:
+          node-version: '22'
+      # Install PostCSS plugins (from your package.json)
+      - run: yarn install
       - name: Setup Ruby
         # https://github.com/ruby/setup-ruby/releases/tag/v1.207.0
         uses: ruby/setup-ruby@4a9ddd6f338a97768b8006bf671dfbad383215f4