Update dependencies for mailman3

From: Einar_Bjarni_Halldórsson <einar_at_isnic.is>
Date: Tue, 04 Jul 2023 23:20:31 UTC
Hi,

Today mailman3 stopped working, probably because of update of 
py-setuptools. Needed dependecies are not listed by mail/mailman3 and 
some are wrong.

I've created two PR to fix the problem.

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=272375 - upgrade 
mail/py-authheaders to latest version and become maintainer
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=272376 - Update 
dependencies for mail/mailman3. Update versions and add missing dependencies

I've built all packages with these changes in poudriere and I'm running 
with them now.

I'd appreciate if a committer could take a look and get these committed 
since the port is broken as-is.

.einar