cirrus-ci: Update FreeBSD release
cirrus-ci: Update FreeBSD release

Unlike Linux distros where every release has a separate set of packages,
FreeBSD's ports system has just one set of packages that's used with every
release. The ports system is only guaranteed to be compatible with the latest
stable and development releases; if you have an older release installed and you
try to update ports before you've updated the base OS, things can break in weird
ways.

Apparently FreeBSD 12.2 was recently released, so our 12.1-based CI runs started
breaking. Bumping the images to 12.2 should fix things.

Somasis/kakoune,casimir/kakoune,casimir/kakoune,jkonecny12/kakoune,danr/kakoune,lenormf/kakoune,Somasis/kakoune,mawww/kakoune,lenormf/kakoune,danr/kakoune,jkonecny12/kakoune,jkonecny12/kakoune,mawww/kakoune,danr/kakoune,mawww/kakoune,Somasis/kakoune,alexherbo2/kakoune,jkonecny12/kakoune,lenormf/kakoune,Somasis/kakoune,casimir/kakoune,lenormf/kakoune,casimir/kakoune,alexherbo2/kakoune,alexherbo2/kakoune,danr/kakoune,mawww/kakoune,alexherbo2/kakoune