chore(deps): update container image bitnami/alertmanager to 0.26.0@ec6a6b3 (#15806)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| bitnami/alertmanager | digest | `3da5256` -> `ec6a6b3` |

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charts/enterprise/prometheus/Chart.yaml

@@ -1,7 +1,7 @@
 kubeVersion: ">=1.24.0"
 apiVersion: v2
 name: prometheus
-version: 13.0.23
+version: 13.0.24
 appVersion: 2.48.0
 description:
   kube-prometheus-stack collects Kubernetes manifests, Grafana dashboards,

charts/enterprise/prometheus/values.yaml

@@ -6,7 +6,7 @@ thanosImage:
   tag: v0.32.5@sha256:3e5c47dd3a0bfc6c595036c1c49c7ca95979a89c1fb93ee4cdee3bf5d296f944
 alertmanagerImage:
   repository: bitnami/alertmanager
-  tag: 0.26.0@sha256:3da5256271a71100d822125dc4af6466f7f2d0a4a1680ba6c01087207be95192
+  tag: 0.26.0@sha256:ec6a6b36356594e486f9cb0461c830123c6c4ca016ae0cdcffcbaaf8e8adb703
 global:
   labels: {}
 workload: