Only bootstrap ports for FreeBSD <= 12.

The portsnap command has apparently gone away in FreeBSD 15.  Since we
only use things from ports for FreeBSD 12 or older, only extract the
ports information for those older releases.

roles/mythtv-freebsd/tasks/main.yml

@@ -7,7 +7,9 @@
 
 - name: bootstrap ports
   command: /usr/sbin/portsnap extract
-  when: not ports_dir.stat.exists
+  when:
+  - not ports_dir.stat.exists
+  - ansible_distribution_major_version|int <= 12
 
 - name: create a list of compilers and build essentials
   set_fact: