Bump version of actions/checkout to v6

Author: uhafner

.github/workflows/sync-labels.yml

@@ -13,7 +13,7 @@ jobs:
     name: Sync Labels
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: brpaz/action-label-syncer@0.2.0
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}