github-ci: update FreeBSD 12 from 12.0 to 12.2 for Python 3

[avtikhon]

Found that python3 installing packages need updated libraries from from 12.2 release 1.
Updated VMs on local test hosts with:

sudo freebsd-update -r 12.2-RELEASE upgrade # set to release
sudo freebsd-update install                 # install downloaded
sudo pkg upgrade -y

Updated snapshot with:

NAME=freebsd_12
VBoxManage snapshot $NAME delete $NAME
VBoxManage: error: This machine does not have any snapshots
VBoxManage snapshot $NAME take $NAME --pause