⬆️ 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/pythonpublish.yaml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Set up Python
       uses: actions/setup-python@v5
       with:

.github/workflows/test_cpac.yaml

@@ -35,7 +35,7 @@ jobs:
         registry: ghcr.io
         username: ${{ github.actor }}
         password: ${{ secrets.GITHUB_TOKEN }}
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
       with:
         fetch-depth: 0
     - name: Clear up some space on runner
@@ -85,7 +85,7 @@ jobs:
         sudo rm -rf /usr/share/dotnet
         sudo rm -rf /opt/ghc
         sudo rm -rf "/usr/local/share/boost"
-    - uses: actions/checkout@v4
+    - uses: actions/checkout@v6
     - name: Set up Go
       uses: actions/setup-go@v5
       with: