chore(deps): update container image bitnami/alertmanager to 0.27.0@a4db120 by renovate (#23929)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [bitnami/alertmanager](https://togithub.com/bitnami/containers)
([source](https://togithub.com/bitnami/containers/tree/HEAD/bitnami/alertmanager))
| digest | `deb4284` -> `a4db120` |

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This PR has been generated by [Renovate
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charts/premium/prometheus/Chart.yaml

@@ -42,4 +42,4 @@ sources:
   - https://hub.docker.com/r/bitnami/prometheus
   - https://quay.io/thanos/thanos
 type: application
-version: 19.3.1
+version: 19.3.2

charts/premium/prometheus/values.yaml

@@ -6,7 +6,7 @@ thanosImage:
   tag: v0.35.1@sha256:3c0ba6e10128e044f47fc4fcfd7652e4a5801a314415c49beedc1f19c364915f
 alertmanagerImage:
   repository: bitnami/alertmanager
-  tag: 0.27.0@sha256:deb42843effd894fc527b15a622d4233baa9c43906b7e31e1ee19f54c662dedf
+  tag: 0.27.0@sha256:a4db1208364ecedb9d30f6333342dd21b07483bbdd8cddfbc1d141fe21d50abb
 global:
   labels: {}
 workload: