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](actions/checkout@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]>

Author: dependabot[bot]

.github/workflows/build-docker-image.yml

@@ -14,7 +14,7 @@ jobs:
       runs-on: ubuntu-latest
       steps:
         - name: Checkout
-          uses: actions/checkout@v4
+          uses: actions/checkout@v6
 
         - name: Set up Docker Buildx
           uses: docker/setup-buildx-action@v3
@@ -48,7 +48,7 @@ jobs:
       runs-on: ubuntu-latest
       steps:
         - name: Checkout
-          uses: actions/checkout@v4
+          uses: actions/checkout@v6
 
         - name: Set up Docker Buildx
           uses: docker/setup-buildx-action@v3

.github/workflows/deploy-cf-pages.yml

@@ -17,7 +17,7 @@ jobs:
         working-directory: frontend
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Node
         uses: actions/setup-node@v4