build(deps): bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](https://github.com/actions/checkout/compare/v4...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/ci-resilience-nightly.yml

@@ -20,7 +20,7 @@ jobs:
     timeout-minutes: 20
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Node.js
         uses: actions/setup-node@v4

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
       matrix:
         node-version: [22, 23]
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Use Node.js ${{ matrix.node-version }}
         uses: actions/setup-node@v4
         with: