Bump actions/checkout from 4.1.4 to 4.1.6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4.1.4 to 4.1.6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@0ad4b8f...a5ac7e5)

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

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

.github/workflows/validate.yml

@@ -20,7 +20,7 @@ jobs:
         sdk: [3.1, stable, beta]
 
     steps:
-      - uses: actions/checkout@0ad4b8fadaa221de15dcec353f45205ec38ea70b
+      - uses: actions/checkout@a5ac7e51b41094c92402da3b24376905380afc29
       - uses: dart-lang/setup-dart@f0ead981b4d9a35b37f30d36160575d60931ec30
         with:
           sdk: ${{ matrix.sdk }}