Bump actions/checkout from 6 to 7 in the all-actions group

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


Updates `actions/checkout` from 6 to 7
- [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/v6...v7)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: all-actions
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/docker-publish-backend.yml

@@ -13,7 +13,7 @@ jobs:
     steps:
       # 1. Récupération du code
       - name: Check out the repo
-        uses: actions/checkout@v6
+        uses: actions/checkout@v7
 
       # 2. Configuration du moteur de Buildx pour les builds multi-plateformes
       - name: Set up Docker Buildx