chore(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/ci.yml

@@ -18,7 +18,7 @@ jobs:
       COMPOSE_PROJECT_NAME: docker-elk
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       #####################################################
       #                                                   #

.github/workflows/docs.yml

@@ -15,7 +15,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
 
       - name: Check links
         uses: UmbrellaDocs/action-linkspector@v1

.github/workflows/update.yml

@@ -17,7 +17,7 @@ jobs:
           - release-8.x
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           ref: ${{ matrix.branch }}
           sparse-checkout-cone-mode: false
@@ -70,7 +70,7 @@ jobs:
       # Removes untracked files created by npm (node_modules/, package.json, ...).
       # Disables previous sparse checkout.
       - name: Clean checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         if: steps.get-latest-release.outputs.result && fromJson(steps.get-latest-release.outputs.result).version != steps.current-release.outputs.version
         with:
           ref: ${{ matrix.branch }}