autodoc mock out monascaclient
autodoc mock out monascaclient

current monascaclient version does not work with osc-lib 1.11.0.
Mock out the module for now until a new monascaclient is released
and put in upper constraints

https://review.openstack.org/#/c/579139/

Change-Id: Id4f7efcd32ec6dbf582b27c4b22ad2f89caa647f

openstack/congress,openstack/congress