Upgrade to FreeBSD 14.0 in CI environment

Author: sio

.ci/cirrus-freebsd.yml.j2

@@ -1,7 +1,7 @@
 task:
   name: 'ci/cirrusci: test-freebsd'
   freebsd_instance:
-    image_family: freebsd-13-2
+    image_family: freebsd-14-0 # https://cirrus-ci.org/guide/FreeBSD/
   env:
     SED: gsed
     PIP_CACHE_DIR: $CIRRUS_WORKING_DIR/cache/pip