build(deps): 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)
- [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/nightly.yml

@@ -27,7 +27,7 @@ jobs:
         with:
           go-version: ${{ env.GO_VERSION }}
 
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           path: src/github.com/containerd/containerd
 
@@ -147,7 +147,7 @@ jobs:
         with:
           go-version: ${{ env.GO_VERSION }}
 
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           path: src/github.com/containerd/containerd