Bump actions/checkout from 2.3.5 to 2.4.0 (#825)

Bumps [actions/checkout](https://github.com/actions/checkout) from 2.3.5 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/v2.3.5...v2.4.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

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

.github/workflows/maven.yml

@@ -30,7 +30,7 @@ jobs:
 #          - java: 18-ea
 #            experimental: true        
     steps:
-    - uses: actions/checkout@v2.3.5
+    - uses: actions/checkout@v2.4.0
     - uses: actions/cache@v2.1.6
       with:
         path: ~/.m2/repository