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] <[email protected]>

Author: dependabot[bot]

.github/workflows/build.yml

@@ -7,7 +7,7 @@ jobs:
     name: Build
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Set up JDK/Maven
         uses: actions/setup-java@v5
         with:

.github/workflows/release.yml

@@ -23,7 +23,7 @@ jobs:
           app-id: ${{ vars.RELEASE_APP_ID }}
           private-key: ${{ secrets.RELEASE_APP_PRIVATE_KEY }}
       - name: Check out from SCM
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           token: ${{ steps.app-token.outputs.token }}
       - name: Import GPG key