Update actions/setup-node action to v6

Author: renovate[bot]

.github/workflows/release-npm.yml

@@ -15,7 +15,7 @@ jobs:
     environment: Release
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-node@v5
+      - uses: actions/setup-node@v6
         with:
           node-version: '24.x'
           cache: 'npm'

.github/workflows/site.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-node@v5
+      - uses: actions/setup-node@v6
         with:
           node-version: 22.x
       - run: npm ci

.github/workflows/test.yml

@@ -23,7 +23,7 @@ jobs:
     steps:
       - uses: actions/checkout@v5
       - name: with Node.js ${{ matrix.node-version }} on ${{ matrix.os }}
-        uses: actions/setup-node@v5
+        uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node-version }}
       - run: npm ci
@@ -36,7 +36,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-node@v5
+      - uses: actions/setup-node@v6
         with:
           node-version: 24.x
       - run: npm ci
@@ -48,7 +48,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-node@v5
+      - uses: actions/setup-node@v6
         with:
           node-version: 24.x
       - run: npm ci