fix(charts): update helm release promtail to v6.16.4

[renovate[bot]]

This PR contains the following updates:

Package	Update	Change
promtail (source)	patch	6.16.3 -> 6.16.4

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Release Notes

grafana/helm-charts (promtail)

### [`v6.16.4`](https://togithub.com/grafana/helm-charts/releases/tag/grafana-6.16.4) [Compare Source](https://togithub.com/grafana/helm-charts/compare/promtail-6.16.3...promtail-6.16.4) The leading tool for querying and visualizing time series and metrics.

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[github-actions[bot]]

:tada: This PR is included in version 16.2.1 :tada:

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