fix(charts): update helm release promtail to v6.16.6

[renovate[bot]]

This PR contains the following updates:

Package	Update	Change
promtail (source)	patch	6.16.5 -> 6.16.6

---

Release Notes

grafana/helm-charts (promtail)

### [`v6.16.6`](https://redirect.github.com/grafana/helm-charts/releases/tag/grafana-6.16.6) [Compare Source](https://redirect.github.com/grafana/helm-charts/compare/promtail-6.16.5...promtail-6.16.6) The leading tool for querying and visualizing time series and metrics.

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.

[github-actions[bot]]

:tada: This PR is included in version 16.8.0 :tada:

The release is available on GitHub release

Your semantic-release bot :package::rocket: