Switch default runtimerepourl to flathub.org
The runtime at cdn.kde.org is outdated (it's still 6.6-kf6preview) and I suppose many nightlies have been switched to 6.6 served by flathub.org.
I just tried to install KTrip and it failed because it referenced the
outdated runtime at cdn.kde.org although it's built against 6.6 from
flathub.org. After changing RuntimeRepo
in the flatpakref file to
https://dl.flathub.org/repo/flathub.flatpakrepo flatpak could successfully
install KTrip and the needed runtime.
We should probably find a way to get the runtime that is actually used for the build instead of using the hardcoded runtime in this file here which will always be out of sync with reality for some project.