Issue 50952 - SSCA lacks basicConstraint:CA
Bug Description:
`capture_output` was introduced in python 3.7 and
on earlier versions this code produces TypeError.
Fix Description:
Make it compatible with python 3.6 by setting `stderr`
and `stdout` to PIPE.
Fixes: https://pagure.io/389-ds-base/issue/50952
Reviewed by: mhonek (Thanks!)