Setup mailman3 server

We want to migrate to mailman3 as mailman2 is basically unmaintained and requires Python 2 which is EOL.

Because the mailman and mailman3 packages conflict and we don't want to perform a big bang migration, mailman3 must be deployed on a separate server. mailman-web (mailman3's web interface) hasn't been packaged yet, so for now we are using my homebrewed PKGBUILD.

[1] https://gist.github.com/klausenbusk/5982063f95c503754a51ed2fefb8915e

Ref #59 (closed)

---

Migrated lists:

• arch-announce
• arch-devops-private
• arch-events
• arch-wiki-admins

roles/mailman3/tasks/main.yml

@@ -10,8 +10,8 @@
     - {src: settings.py.j2, dest: /etc/mailman3/settings.py, group: mailman-web}
     - {src: urls.py.j2, dest: /etc/mailman3/urls.py, group: mailman-web}
   notify:
-   - reload mailman
-   - restart mailman-web
+    - reload mailman
+    - restart mailman-web
 
 - name: install mailman postfix.cfg configuration
   copy: src=postfix.cfg dest=/etc/postfix.cfg owner=root group=root mode=0644