[mailman3] Install django-allauth-cas from PIP

Signed-off-by: Yohann D'ANELLO <ynerant@crans.org>

roles/mailman3/tasks/main.yml

 ---
-# You will need to do after: sudo pip3 install django-allauth-cas
-# Yes, it is horrible but we need Debian Python3 to see this django app.
 - name: Install mailman3
   apt:
     update_cache: true
@@ -16,10 +14,13 @@
   retries: 3
   until: apt_result is succeeded
 
+- name: Install django-allauth-cas from PIP
+  pip:
+    name: django-allauth-cas
+
 # You will need to setup postgres
 # sudo -u postgres createuser -P mailman3
 # sudo -u postgres createdb -O mailman3 mailman3
-# Test with: psql -U mailman3 -W -d mailman3 -h localhost
 - name: Configure mailman3
   template:
     src: "mailman3/{{ item }}.j2"
@@ -42,7 +43,6 @@
 # You will need to setup postgres
 # sudo -u postgres createuser -P mailman3web
 # sudo -u postgres createdb -O mailman3web mailman3web
-# Test with: psql -U mailman3web -W -d mailman3web -h localhost
 # Then migrate data: sudo /usr/share/mailman3-web/manage.py migrate
 - name: Configure mailman3-web
   template: