Fix the appimage build
Review Request #1194 — Created Dec. 18, 2021 and submitted
This required some tweaks in the image which I already pushed, but these changes make it work with both convey 0.13 and 0.15-dev
Build on my dev machine with convey 0.15-dev and on one of the build agents with convey 0.13
I did also run the appimage and verify that it does in fact work!