Add Qt 6 CI
This disables the date/time KCM due to still depending on KDELibs4Support when building against Qt 6. To avoid that getting forgotten it is set up to fail hard once the Plasma major version is bumped.
This disables the date/time KCM due to still depending on KDELibs4Support when building against Qt 6. To avoid that getting forgotten it is set up to fail hard once the Plasma major version is bumped.