cirrus: test over newer FreeBSD 12 release

Author: xdelaruelle

.cirrus.yml

@@ -82,7 +82,7 @@ task:
   freebsd_instance:
     matrix:
       image_family: freebsd-11-4
-      image_family: freebsd-12-2
+      image_family: freebsd-12-3
     cpu: 1
     memory: 2G
   reqinstall_script: pkg install -y bash wget gmake dejagnu py38-sphinx tcl86 tcl-wrapper autoconf ksh93 zsh fish perl5 python38 ruby cmake R readline