Mark mail_relay as working (#3430)

Update the mail_relay catalog entry in apps.toml.

This changes its state from inprogress to working.

Author: rungeard

apps.toml

@@ -3021,7 +3021,7 @@ url = "https://github.com/YunoHost-Apps/mailman3_ynh"
 [mail_relay]
 added_date = 1776180342 # 2026/04/14
 category = "communication"
-state = "inprogress"
+state = "working"
 subtags = [ "email" ]
 url = "https://github.com/YunoHost-Apps/mail_relay_ynh"