Merge pull request #408 from ruby-syntax-tree/dependabot/github_actions/actions/checkout-4

Bump actions/checkout from 3 to 4

Author: github-actions[bot]

.github/workflows/gh-pages.yml

@@ -25,7 +25,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Setup Pages
         uses: actions/configure-pages@v3
       - name: Set up Ruby