Bump actions/checkout from 3.6.0 to 4.1.0 (#159)

Bumps [actions/checkout](https://github.com/actions/checkout) from 3.6.0 to 4.1.0.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@f43a0e5...8ade135)

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

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

Author: dependabot[bot]

.github/workflows/validate.yml

@@ -20,7 +20,7 @@ jobs:
         sdk: [3.0.0, stable, beta]
 
     steps:
-      - uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744
+      - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608
       - uses: dart-lang/setup-dart@8a4b97ea2017cc079571daec46542f76189836b1
         with:
           sdk: ${{ matrix.sdk }}