[mailman3] Add fedmsg archiver

Plenty of existing archived lists are reliable on fedmsg archiver. The EPEL9
package is currently in bodhi
https://bodhi.fedoraproject.org/updates/FEDORA-EPEL-2024-39533b3dcb. Let's add
it to mailman3 role.

Signed-off-by: Michal Konecny <mkonecny@redhat.com>

roles/mailman3/tasks/main.yml

@@ -15,6 +15,7 @@
     - postorius
     - python3-gunicorn
     - python3-mailman-hyperkitty
+    - python3-mailman3-fedmsg-plugin
     - python3-mailman-web
     - python3-mod_wsgi
     - python3-pylibmc

roles/mailman3/templates/mailman.cfg.j2

@@ -34,6 +34,13 @@ class: mailman_hyperkitty.Archiver
 enable: yes
 configuration: /etc/mailman3.d/hyperkitty.cfg
 
+[archiver.fedmsg]
+class: mailman3_fedmsg_plugin.Archiver
+enable: yes
+
+[archiver.prototype]
+enable: yes
+
 [webservice]
 hostname: localhost
 port: 8001