Bump actions/checkout from 5 to 6 in the development-dependencies group

Bumps the development-dependencies group with 1 update: [actions/checkout](https://github.com/actions/checkout).


Updates `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
  dependency-group: development-dependencies
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/ci-snapshot.yml

@@ -29,12 +29,12 @@ jobs:
           ports: '5672:5672 15672:15672 5552:5552'
           plugins: rabbitmq_stream,rabbitmq_management,rabbitmq_delayed_message_exchange,rabbitmq_consistent_hash_exchange
 
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         with:
           show-progress: false
 
       - name: Checkout Common Repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: spring-io/spring-github-workflows
           path: .github/spring-github-workflows

.github/workflows/verify-staged-artifacts.yml

@@ -27,7 +27,7 @@ jobs:
           plugins: rabbitmq_stream,rabbitmq_management
 
       - name: Checkout Spring Integration Repo
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           repository: spring-projects/spring-integration
           show-progress: false