python3-pdns package requires python=>3.8

[dumprop]

Description

The python3-pdns library has recently been added, which requires a version of at least 3.8, so it breaks default installation on ubuntu 16.04/18.04 (there python 3.6)

1. pip install -r python3-pdns

Expected behavior

yeti installed on ubuntu 16.04/18.04, which are specified in the documentation

Actual behavior

yeti installation breaks on python3-pdns installation

So, needs migration to ubuntu 20.04 / docs update

In fact this library used only in PassiveDNS feed

Could be related https://github.com/yeti-platform/yeti/issues/690

Also, there is possible problem in the future: ipwhois 1.2.0 requires dnspython<=2.0.0, but you'll have dnspython 2.2.1 which is incompatible.