chore(deps): bump the github-actions group across 1 directory with 2 updates

Bumps the github-actions group with 2 updates in the / directory: [actions/checkout](https://github.com/actions/checkout) and [DavidAnson/markdownlint-cli2-action](https://github.com/davidanson/markdownlint-cli2-action).


Updates `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)

Updates `DavidAnson/markdownlint-cli2-action` from 16 to 23
- [Release notes](https://github.com/davidanson/markdownlint-cli2-action/releases)
- [Commits](DavidAnson/markdownlint-cli2-action@v16...v23)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: github-actions
- dependency-name: DavidAnson/markdownlint-cli2-action
  dependency-version: '23'
  dependency-type: direct:production
  update-type: version-update:semver-major
  dependency-group: github-actions
...

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

Author: dependabot[bot]

.github/workflows/docker-ci.yml

@@ -97,7 +97,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup Docker Buildx
         uses: docker/setup-buildx-action@v4
@@ -353,7 +353,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Setup QEMU
         uses: docker/setup-qemu-action@v4

.github/workflows/docs-ci.yml

@@ -26,10 +26,10 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Lint Markdown files
-        uses: DavidAnson/markdownlint-cli2-action@v16
+        uses: DavidAnson/markdownlint-cli2-action@v23
         with:
           globs: |
             **/*.md
@@ -46,7 +46,7 @@ jobs:
 
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
 
       - name: Check links in markdown files
         uses: gaurav-nelson/github-action-markdown-link-check@v1

.github/workflows/keepalive.yml

@@ -9,7 +9,7 @@ jobs:
   create-keepalive-commit:
       runs-on: ubuntu-latest
       steps:
-        - uses: actions/checkout@v4
+        - uses: actions/checkout@v6
         - name: Keepalive Workflow
           # You may pin to the exact commit or the version.
           # uses: gautamkrishnar/keepalive-workflow@c85efc9567a3dadb9b9d4e116aa891f76c0ef7e6