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:
         working-directory: org.knime.ui.js
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
         # Sonar runs in Jenkins for the whole repo due to the mix of Java and JS
         # with:
         #   fetch-depth: 0 # full history for SonarCloud
@@ -66,7 +66,7 @@ jobs:
       options: --user 1001
 
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: pnpm/action-setup@v4
         with:
           package_json_file: org.knime.ui.js/package.json

.github/workflows/copilot-setup-steps.yml

@@ -24,7 +24,7 @@ jobs:
 
     steps:
       - name: Checkout code
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
 
       - uses: pnpm/action-setup@v4
         with: