setup.py: downgrade cx_freeze
cx_freeze 6.11 breaks tkinter/tcl on Linux. This commit can be cherry-picked to fix the AppImage, but maybe this will be fixed once cx_freeze 6.12 is out, see https://github.com/marcelotduarte/cx_Freeze/commit/7222589da65edef2583eb88a7d02ae8524c01466 so we should maybe just wait.
For now, as we just had a release we can wait and hopefully remember to keep an eye on it.
Yeah, would like to keep it as draft as a reminder and as a work-around should someone need to build an AppImages in the meantime.
Successfully used this for the 0.3.4 AppImage in appimage-0-3-4 branch. I opened a discussion at https://github.com/marcelotduarte/cx_Freeze/discussions/1576 to track this in cx_freeze as well.
Work-around, other than downgrading: pip install cx-freeze --no-binary cx-freeze on a machine that has tk8.6 installed, so that would work on our runner.
Actual fix is on the way and hopefully working by the time the next version of cx is released.