qa/tasks/workunit: fix no module named 'pipes'
Python 3.13 finally dropped the 'pipes' module,
replacing it with shlex.
Fixes: https://tracker.ceph.com/issues/73498
Signed-off-by: Kyr Shatskyy <kyrylo.shatskyy@clyso.com>
(cherry picked from commit
da40484b9577aba21833e6b09c6129fe2d3c596c)