Use mise with Ruby 3.4.9

Author: hschne

.github/workflows/jekyll.yml

@@ -20,6 +20,8 @@ jobs:
     steps:
       - name: Checkout
         uses: actions/checkout@v4
+      - name: Install mise
+        uses: jdx/mise-action@v2
       - name: Setup Ruby
         uses: ruby/setup-ruby@v1
         with:

.mise.toml

@@ -0,0 +1,2 @@
+[tools]
+ruby = "3.4.9"