Cirrus: use 4 CPUs for FreeBSD
Cirrus: use 4 CPUs for FreeBSD

Currently, FreeBSD jobs are using 2 cores and take about 30 minutes to
run. However, we only have two jobs, and Cirrus allows for 8 concurrent
CPUs. So let's bump our usage to take the full advantage of the
resources we're given.

der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat,der-lyse/newsboat,der-lyse/newsboat,der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,der-lyse/newsboat,newsboat/newsboat,der-lyse/newsboat,newsboat/newsboat,newsboat/newsboat,newsboat/newsboat