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)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v3...v4)

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

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

.github/workflows/docs.yaml

@@ -12,6 +12,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       - name: Build and push docs
         uses: athackst/[email protected]

.github/workflows/ros.yaml

@@ -12,7 +12,7 @@ jobs:
     steps:
       - 
         name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       -
         name: Test
         uses: ./.github/actions/test/
@@ -27,7 +27,7 @@ jobs:
     steps:
       - 
         name: Checkout code
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
       -
         name: Run linter
         uses: ./.github/actions/lint/