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] <support@github.com>

Author: dependabot[bot]

.github/workflows/cd.yml

@@ -29,7 +29,7 @@ jobs:
     name: Deploy
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: docker/setup-buildx-action@v3
       - uses: docker/build-push-action@v6
         with:

.github/workflows/ci.yml

@@ -11,7 +11,7 @@ jobs:
     name: Check
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
@@ -26,7 +26,7 @@ jobs:
     name: Test Suite
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
@@ -41,7 +41,7 @@ jobs:
     name: Rustfmt
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
@@ -58,7 +58,7 @@ jobs:
     name: Clippy
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: actions-rs/toolchain@v1
         with:
           profile: minimal
@@ -75,7 +75,7 @@ jobs:
     name: Docker Build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
       - name: Build and push