Change deprecated BaseImage to Image

Signed-off-by: Benjamin <benjamin@yunify.com>

jsonnet/kube-prometheus/alertmanager/alertmanager.libsonnet

@@ -141,7 +141,7 @@ local k = import 'ksonnet/ksonnet.beta.4/k.libsonnet';
         spec: {
           replicas: $._config.alertmanager.replicas,
           version: $._config.versions.alertmanager,
-          baseImage: $._config.imageRepos.alertmanager,
+          image: $._config.imageRepos.alertmanager + ':' + $._config.versions.alertmanager,
           nodeSelector: { 'kubernetes.io/os': 'linux' },
           serviceAccountName: 'alertmanager-' + $._config.alertmanager.name,
           securityContext: {