Merge branch 'pb/use-freebsd-12.3-in-cirrus-ci'

Update the version of FreeBSD image used in Cirrus CI.

* pb/use-freebsd-12.3-in-cirrus-ci:
  ci: update Cirrus-CI image to FreeBSD 12.3

Author: gitster

.cirrus.yml

@@ -9,7 +9,7 @@ freebsd_12_task:
     DEFAULT_TEST_TARGET: prove
     DEVELOPER: 1
   freebsd_instance:
-    image_family: freebsd-12-2
+    image_family: freebsd-12-3
     memory: 2G
   install_script:
     pkg install -y gettext gmake perl5