Quoting Philipp Meisberger <team@pm-codeworks.de>:
Oh OK. But this is necessary as my other package libpam-rfid is based on libpam-python which only supports writing PAM modules in Python 2.
Maybe you should port it to Python 3 then? Python 2 will be supported in Debian 10 (buster), but certainly not later. You can probably still have backports, but it is a dead end. I have the same trouble, because I'm co-maintainer of e.g. sat-pubsub and trac. Either upstream ports to Python 3 soon or I will have to ask for removing them from Debian. See https://pythonclock.org/