Update actions/checkout action to v7

Author: renovate[bot]

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Setup Node
         uses: actions/setup-node@v6
@@ -66,7 +66,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       - name: Format Markdown with markdownlint
         run: |