Bump actions/checkout from 5.0.1 to 6.0.0 (#1450)

Bumps [actions/checkout](https://github.com/actions/checkout) from 5.0.1 to 6.0.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Commits](actions/checkout@v5.0.1...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/_ci.yml

@@ -36,7 +36,7 @@ jobs:
       packages: read
     runs-on: ubuntu-22.04
     steps:
-    - uses: actions/checkout@v5.0.1
+    - uses: actions/checkout@v6.0.0
     - name: Configure repo Bazel settings
       run: |
         echo "build:remote-envoy-engflow --config=bes-envoy-engflow" > repo.bazelrc