Bump actions/checkout from 4 to 6 (#147)

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]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci.yml

@@ -47,7 +47,7 @@ jobs:
       image: registry.opensuse.org/documentation/containers/15.6/opensuse-daps-toolchain:latest
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Get dependencies
         run: |
@@ -175,7 +175,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       # Set up Python on macOS environment
       - name: Setup Python

.github/workflows/gh-pages.yml

@@ -15,7 +15,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Install Graphviz
         run: sudo apt-get update && sudo apt-get install -y graphviz

.github/workflows/release.yml

@@ -43,7 +43,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Check Version Consistency
         id: version_check

.github/workflows/ruff.yml

@@ -10,7 +10,7 @@ jobs:
   ruff:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       # Check for formatting errors (but don't fix them)
 
       - uses: astral-sh/ruff-action@v3