chore(deps): update loki to v6.19.0 (#990)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [loki](https://grafana.github.io/helm-charts)
([source](https://redirect.github.com/grafana/helm-charts)) | minor |
`6.18.0` -> `6.19.0` |

---

### Release Notes

<details>
<summary>grafana/helm-charts (loki)</summary>

###
[`v6.19.0`](https://redirect.github.com/grafana/helm-charts/releases/tag/grafana-6.19.0)

The leading tool for querying and visualizing time series and metrics.

</details>

---

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rebase/retry checkbox.

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---

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src/loki/common/zarf.yaml

@@ -16,7 +16,7 @@ components:
         localPath: ../chart
       - name: loki
         url: https://grafana.github.io/helm-charts/
-        version: 6.18.0
+        version: 6.19.0
         namespace: loki
         valuesFiles:
           - ../values/values.yaml