Update actions/setup-node action to v6

Author: renovate[bot]

.github/workflows/ci.yml

@@ -27,7 +27,7 @@ jobs:
           - 26.x
     steps:
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v3
+        uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node-version }}
       - name: Ensure line endings are consistent
@@ -55,7 +55,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Use Node.js
-        uses: actions/setup-node@v3
+        uses: actions/setup-node@v6
         with:
           node-version: 24.x
       - name: Check out repository