Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/test.yml

@@ -10,6 +10,6 @@ jobs:
     runs-on: ubuntu-latest
     if: github.event_name == 'push' || (github.event_name == 'pull_request' && !startsWith(github.head_ref, 'renovate/'))
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - run: yarn
       - run: yarn test:ci