[stable/prometheus] Fix #5425 (#5591)

* Fix #5425

* Increment chart version for #5425

stable/prometheus/Chart.yaml

@@ -1,5 +1,5 @@
 name: prometheus
-version: 6.6.1
+version: 6.6.2
 appVersion: 2.2.1
 description: Prometheus is a monitoring system and time series database.
 home: https://prometheus.io/

stable/prometheus/templates/server-configmap.yaml

@@ -15,7 +15,7 @@ data:
   {{ $key }}: |
 {{ toYaml $value | default "{}" | indent 4 }}
 {{- if eq $key "prometheus.yml" -}}
-{{ if $root.Values.alertmanager.enabled }}
+{{- if $root.Values.alertmanager.enabled }}
     alerting:
       alertmanagers:
       - kubernetes_sd_configs: