Properly version ksycoca files
This allows to use a different format for the KF6 data, which is needed because we dropped service types
This means that when someone updates the cache manually both 5 and 6 data needs to be updated
This allows to use a different format for the KF6 data, which is needed because we dropped service types
This means that when someone updates the cache manually both 5 and 6 data needs to be updated