Bump actions/checkout from 1 to 2.4.0

Bumps [actions/checkout](https://github.com/actions/checkout) from 1 to 2.4.0.
- [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/v1...v2.4.0)

---
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/labeler.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Check out the repository
-        uses: actions/checkout@v2.3.4
+        uses: actions/checkout@v2.4.0
 
       - name: Run Labeler
         uses: crazy-max/ghaction-github-labeler@v3.1.1