Bump actions/checkout from 4.1.1 to 4.2.1

Bumps [actions/checkout](https://github.com/actions/checkout) from 4.1.1 to 4.2.1.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@b4ffde6...eef6144)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/testing.yml

@@ -43,7 +43,7 @@ jobs:
           go-version: ${{ matrix.go }}
 
       - name: Check out code into the Go module directory
-        uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
+        uses: actions/checkout@eef61447b9ff4aafe5dcd4e0bbf5d482be7e7871 # v4.2.1
         with:
           persist-credentials: false
           fetch-depth: 0