monitoring-alertmanager-config: quote matchType =, was YAML value-tag

PyYAML parses bare `=` as the YAML 1.1 value tag and rejects it as a
scalar in matchType. Quote it.

Author: tillo

monitoring-alertmanager-config/alertmanager-config.yml

@@ -13,7 +13,7 @@ spec:
     matchers:
     - name: team
       value: mdapi
-      matchType: =
+      matchType: "="
     groupBy: [component, alertname]
     groupWait: 30s
     groupInterval: 5m