prometheus/alertmanager: update to 0.27.0

prometheus/map.jinja

 {% set prometheus = salt['grains.filter_by']({
     'default': {
       'release': '2.51.1',
-      'alertmanager_release': '0.26.0',
+      'alertmanager_release': '0.27.0',
       'node_exporter_release': '1.7.0',
     }
 }, grain='os_family', merge=salt['pillar.get']('prometheus')) %}