[crossfire] Crossfire 1.75.0 release engineering

[Kevin Zheng]

Hi folks,

I am thinking about cutting a 1.75.0 release in the next couple of days. 
I would like to coordinate a full server/maps/arch release as well as 
releases for both the GTKv2 and JXClient.

This release is a good time for those running servers to switch to 
Python 3, before some major code rework in the server.

This will also be the last GTKv2 client using Gtk+2, since Gtk+2 is now 
officially EoL'ed (future GTK client releases will use Gtk3).

I would certainly appreciate an extra set of eyes testing the server 
Python (after the Python 2 migration) and checking the GTK client builds.

Thanks in advance, and happy 2021.

Regards,
Kevin