Update actions/setup-node action to v6

Author: renovate[bot]

.github/workflows/markdown-lint.yml

@@ -27,7 +27,7 @@ jobs:
         uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
 
       - name: Set up Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node-version }}
 

.github/workflows/prettier-json.yml

@@ -17,7 +17,7 @@ jobs:
       - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
 
       - name: Set up Node.js
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@v6
         with:
           node-version: 24.x