Bump actions/checkout from 4 to 5

Bumps [actions/checkout](https://github.com/actions/checkout) from 4 to 5.
- [Release notes](https://github.com/actions/checkout/releases)
- [Changelog](https://github.com/actions/checkout/blob/main/CHANGELOG.md)
- [Commits](actions/checkout@v4...v5)

---
updated-dependencies:
- dependency-name: actions/checkout
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/check.yml

@@ -19,7 +19,7 @@ jobs:
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
       - name: Check test/consistent.bib
         uses: ./
         with:
@@ -34,7 +34,7 @@ jobs:
         if: steps.inconsistent.outcome == 'success'
         run: exit 1
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
         with:
           repository: JabRef/jabref-demonstration-libraries
           path: jabref-demonstration-libraries