Bump actions/checkout from 5 to 6 in the github-actions group

Bumps the github-actions group with 1 update: [actions/checkout](https://github.com/actions/checkout).


Updates `actions/checkout` from 5 to 6
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

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

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

Author: dependabot[bot]

.github/workflows/ci_lin.yml

@@ -20,7 +20,7 @@ jobs:
     steps:
     - name: 'PR commits + 1'
       run: echo "PR_FETCH_DEPTH=$(( ${{ github.event.pull_request.commits }} + 1 ))" >> "${GITHUB_ENV}"
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
       with:
         ref: ${{ github.event.pull_request.head.sha }}
         persist-credentials: false