chore(deps): update actions/checkout action to v6 (#31)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.forgejo/workflows/publish-api.yml

@@ -12,7 +12,7 @@ jobs:
     env:
       CODEBERG_TOKEN: ${{ secrets.PACKAGES_TOKEN }}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Set up JDK 21
         uses: actions/setup-java@v5
         with: