[prometheus] Update Helm release alertmanager to 1.26.* (#6113)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

charts/prometheus/Chart.lock

@@ -1,7 +1,7 @@
 dependencies:
 - name: alertmanager
   repository: https://prometheus-community.github.io/helm-charts
-  version: 1.25.0
+  version: 1.26.0
 - name: kube-state-metrics
   repository: https://prometheus-community.github.io/helm-charts
   version: 6.3.0
@@ -11,5 +11,5 @@ dependencies:
 - name: prometheus-pushgateway
   repository: https://prometheus-community.github.io/helm-charts
   version: 3.4.1
-digest: sha256:1363536cf77f65272d9577dc185bb13cf27637de273fe0a61edc306500afe25f
-generated: "2025-09-03T09:16:37.036687066Z"
+digest: sha256:1bd0c51ff42b9665ea5c39c072cf1b75bda2a48afa18a2346f12df421252f36f
+generated: "2025-09-03T20:48:30.070200323Z"

charts/prometheus/Chart.yaml

@@ -2,7 +2,7 @@ apiVersion: v2
 name: prometheus
 # renovate: github=prometheus/prometheus
 appVersion: v3.5.0
-version: 27.34.0
+version: 27.35.0
 kubeVersion: ">=1.19.0-0"
 description: Prometheus is a monitoring system and time series database.
 home: https://prometheus.io/
@@ -32,7 +32,7 @@ maintainers:
 type: application
 dependencies:
   - name: alertmanager
-    version: "1.25.*"
+    version: "1.26.*"
     repository: https://prometheus-community.github.io/helm-charts
     condition: alertmanager.enabled
   - name: kube-state-metrics