This upgrades our images to Alpine 3.20, Django 4.2, Mailman 3.3.10,
Postorius 1.3.13, Hyperkitty 1.3.12 and django-mailman3 1.3.15.
Files are re-synced with upstream (either container or project)
files, with versions and any alterations noted.
Change-Id: I78d37c0635d38ecfc1d1143a69892fe8d8685214