patch 9.0.1912: Cirrus-CI running out of credits

patch 9.0.1912: Cirrus-CI running out of credits

Problem:  Cirrus-CI running out of credits
Solution: disable Cirrus-CI for now

We are running out of credits for Cirrus CI already at the middle of the
month and unfortunately this means our CI now consistently fails. This
all hapens because cirrus ci is not enforcing the free-tier limits (see also
https://cirrus-ci.org/blog/2023/07/17/limiting-free-usage-of-cirrus-ci/).

Perhaps at the beginning of the next month we can revisit and
enable just a build without testing it.  Hopefully this is won't take
too many credits and we can at least verify that building works.

Signed-off-by: Christian Brabandt <cb@256bit.org>