Bump dessant/lock-threads from 5 to 6

Bumps [dessant/lock-threads](https://github.com/dessant/lock-threads) from 5 to 6.
- [Release notes](https://github.com/dessant/lock-threads/releases)
- [Changelog](https://github.com/dessant/lock-threads/blob/main/CHANGELOG.md)
- [Commits](https://github.com/dessant/lock-threads/compare/v5...v6)

---
updated-dependencies:
- dependency-name: dessant/lock-threads
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

.github/workflows/lock.yml

@@ -8,7 +8,7 @@ jobs:
   lock:
     runs-on: ubuntu-latest
     steps:
-      - uses: dessant/lock-threads@v5
+      - uses: dessant/lock-threads@v6
         with:
           github-token: ${{ github.token }}
           issue-inactive-days: 45