chore(deps): update docker.io/mwader/postfix-relay docker tag to v1.2.1

library/compose/wazuh/compose.yaml.j2

@@ -131,7 +131,7 @@ services:
 
 # --> (Optional) When you need to use an SMTP relay for email notifications, and authentication is required
 # postfix:
-#   image: docker.io/mwader/postfix-relay:1.1.40
+#   image: docker.io/mwader/postfix-relay:1.2.1
 #   environment:
 #     - POSTFIX_myhostname=postfix
 #   volumes: