Bump actions/checkout from 3 to 4

Bumps [actions/checkout](https://github.com/actions/checkout) from 3 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

.github/workflows/docker-image.yml

@@ -24,9 +24,9 @@ jobs:
       pre_release: ${{ steps.repo_status.outputs.pre_release }}
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Checkout nanosaur tools repo
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
       with:
         repository: rnanosaur/nanosaur_tools
         path: nanosaur_tools
@@ -97,7 +97,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - name: Checkout code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Build project
       run: |
         bash nanosaur_description/scripts/nanosaur_stl.sh
@@ -118,7 +118,7 @@ jobs:
     needs: [docker]
     steps:
     - name: Checkout
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Docker Hub Description # https://github.com/peter-evans/dockerhub-description
       uses: peter-evans/dockerhub-description@v3
       with: