Update dessant/lock-threads action to v6 (#2791)

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

.github/workflows/lock-threads.yml

@@ -15,7 +15,7 @@ jobs:
   action:
     runs-on: ubuntu-latest
     steps:
-      - uses: dessant/lock-threads@v5
+      - uses: dessant/lock-threads@v6
         with:
           issue-inactive-days: '1'
           process-only: 'issues'