build(deps): bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...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/deploy_docker_hub.yml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out codebase
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set environment variables
         run: |

.github/workflows/test_systemd.yml

@@ -21,7 +21,7 @@ jobs:
     continue-on-error: ${{ inputs.continue-on-error }}
     steps:
       - name: Check out codebase
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Set environment variables
         run: |

.github/workflows/update_base_digest.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out codebase
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - name: Pull the latest image digest
         id: base_digest