pythongh-91960: Disable Cirrus CI for now (python#109457)

Python is out of free credit and so all jobs are reported as failure.

Rename .cirrus.yml to .cirrus-DISABLED.yml to disable the job.

Author: vstinner

.cirrus.yml .cirrus-DISABLED.yml

@@ -1,3 +1,6 @@
+# gh-91960: Job disabled since Python is out of free credit (September 2023):
+# https://discuss.python.org/t/freebsd-gets-a-new-cirrus-ci-github-action-job-and-a-new-buildbot/33122/26
+
 freebsd_task:
   freebsd_instance:
     matrix: