Bump actions/checkout from 2 to 4 (#14)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2 to 4.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v2...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/unit-test.yaml

@@ -18,7 +18,7 @@ jobs:
         go-version: ^1.19
 
     - name: Check out code into the Go module directory
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
 
     - name: Test
       run: |