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](https://github.com/actions/checkout/compare/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/ci.yml

@@ -16,7 +16,7 @@ jobs:
     env:
       CGO_ENABLED: 0
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up Go
         uses: actions/setup-go@v4
         with:
@@ -47,7 +47,7 @@ jobs:
     name: lint
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up Go
         uses: actions/setup-go@v4
         with:
@@ -62,7 +62,7 @@ jobs:
     runs-on: ubuntu-latest
     needs: [ compile ]
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - name: Set up Go
         uses: actions/setup-go@v4
         with:
@@ -105,7 +105,7 @@ jobs:
     if: github.event_name != 'push' || github.actor != 'dependabot[bot]' && github.actor != 'dependabot-preview[bot]' && github.actor != 'dependabot'
     steps:
       - name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Run Trivy vulnerability scanner in repo mode
         uses: aquasecurity/trivy-action@master
         with:
@@ -132,7 +132,7 @@ jobs:
       GOCOVERDIR: coverage
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Set up Go
         uses: actions/setup-go@v4
         with:
@@ -190,7 +190,7 @@ jobs:
       - name: Checkout matching branch for Dockerfiles (optional)
         id: checkout-dockerfiles
         if: steps.branch-name.outputs.is_default == 'false'
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
         continue-on-error: true
         with:
           repository: openHPI/dockerfiles