Quote default alertmanager null reciever

seeh ttps://github.com/bitnami/charts/issues/4596#issuecomment-741746605

Quote default alertmanager null reciever
2b11129e · Varac · 913aae6b · 2b11129e
Unverified Commit 2b11129e authored 3 years ago by Varac
--- a/ansible/roles/apps/templates/settings/prometheus-stack.yaml
+++ b/ansible/roles/apps/templates/settings/prometheus-stack.yaml
@@ -45,7 +45,7 @@ alertmanager:
      {% if outgoing_mail.enabled %}
      receiver: email
      {% else %}
-      receiver: null
+      receiver: 'null'
      {% endif %}
      routes:
      - match: