Update actions/checkout action to v6 (#2928)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
       - uses: styfle/cancel-workflow-action@0.12.1
         with:
           access_token: ${{ github.token }}
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
         with:
           node-version-file: '.nvmrc'