docs: cdomain.py: get rid of a warning since version 1.8

There's a new warning about a deprecation function. Add a
logic at cdomain.py to avoid that.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
1 file changed