Build(deps): Bump actions/checkout from 5 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 5 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v5...v6)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/docker.yml

@@ -38,7 +38,7 @@ jobs:
           platform=$(uname -m)
           echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - name: Docker meta
         id: meta
         uses: docker/metadata-action@v5

.github/workflows/test.yml

@@ -37,7 +37,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     steps:
       - name: Checkout rmw
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: theimpossibleastronaut/rmw
 
@@ -48,7 +48,7 @@ jobs:
           fi
 
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           path: _linuxdeploy_test
           fetch-depth: 0