* Switch to Qt6 builds.
* Use cmake for builds, qmake is no longer supported as a build tool by upstream.
* Pass CMAKE_SKIP_INSTALL_RPATH option to cmake to avoid rpaths in final executable.
* Drop Qt5 build support.
* Use ninja for build.
* Switch to obs_scm service (instead of tar_scm).
OBS-URL: https://build.opensuse.org/package/show/Education/goldendict-ng?expand=0&rev=10
