chore(deps): bump actions/checkout from 5.0.0 to 6.0.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 5.0.0 to 6.0.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](08c6903cd8...1af3b93b68)

---
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] <support@github.com>

.github/workflows/gpu_code_validation_tests.yml

@@ -79,7 +79,7 @@ jobs:
             gcc: 11 
     steps:
       - name: Checkout tfhe-rs
-        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+        uses: actions/checkout@1af3b93b6815bc44a9784bd300feb67ff0d1eeb3
         with:
           persist-credentials: 'false'
           token: ${{ env.CHECKOUT_TOKEN }}