Bump actions/checkout from 3 to 4 (#70)

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

.github/workflows/merge-to-main.yaml

@@ -17,7 +17,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Log in to container registry
         uses: docker/login-action@v2
         with:

.github/workflows/pr-checks.yaml

@@ -21,7 +21,7 @@ jobs:
       uses: vmware-tanzu/carvel-setup-action@v1
 
     - name: Checkout code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
 
     - name: Install kind
       run: |
@@ -81,7 +81,7 @@ jobs:
         python-version: "3.10"
         architecture: "x64"
     - name: Checkout code
-      uses: actions/checkout@v3
+      uses: actions/checkout@v4
     - name: Run linting checks
       run: |
         ./setup.sh