Bug#1084246: probably caused by pytz.timezone + datetime.datetime

[Rebecca N. Palmer]

Passing pytz.timezone objects directly to datetime.datetime is not 
recommended by pytz upstream, and has probably never worked if they are 
non-constant-offset.  Recent changes to tzdata (see bug 1084190, but 
please do not close it as it affects several packages) made some 
previously constant-offset names non-constant-offset.

A fix is to instead use a plain datetime.timezone, e.g. see here for 
dateparser:
https://salsa.debian.org/python-team/packages/dateparser/-/merge_requests/2