Finally: Admin4 V3 is out!
V3 is implemented in Python3.7+, so it should work for quite a while on recent systems.
While development was homed on github for quite a while already, new releases won't be uploaded to sourceforge any more, and the old update infrastructure is defunct. Instead, releases are available at https://github.com/andreas-p/admin4/releases, and docker container may be easily pulled from dockerhub.
Some functional updates are on-board as well: PostgreSQL 14 has been tested, supporting partitioning.