chore(deps): update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/test.yml

@@ -9,7 +9,7 @@ jobs:
         node-version: [ 18, 20 ]
     steps:
       - name: checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: setup Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@v5
         with: