Bump actions/checkout from 4 to 6

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 6.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...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] <[email protected]>

Author: dependabot[bot]

.github/workflows/comment-on-pr.yaml

@@ -17,7 +17,7 @@ jobs:
       pull-requests: write
     steps:
       - name: Check out repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Initial PR comment
         uses: marocchino/sticky-pull-request-comment@v2

.github/workflows/delete-closed-pr-docs.yaml

@@ -18,7 +18,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Check out repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
 

.github/workflows/deploy-docs.yaml

@@ -38,7 +38,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Check out repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           fetch-depth: 0
           ref: ${{ github.event.pull_request.head.sha }}

.github/workflows/pre-commit.yaml

@@ -24,7 +24,7 @@ jobs:
           private_key: ${{ secrets.PRIVATE_KEY }}
 
       - name: Check out repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           ref: ${{ github.event.pull_request.head.ref }}
 

.github/workflows/spell-check-differential.yaml

@@ -16,7 +16,7 @@ jobs:
     runs-on: ubuntu-22.04
     steps:
       - name: Check out repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Run spell-check
         uses: autowarefoundation/autoware-github-actions/spell-check@v1