Promote python-cmd2-1.4.0 to wallaby-testing
Promote python-cmd2-1.4.0 to wallaby-testing

python-cmd2 in u-c is 1.4.0, this has some new features used by
cliff module.
The update is needed for cliff-3.5.0[1], forked in rdo-common as
setuptools_scm >= 3.0 is not available in CentOS8, to avoid overriding
it in RDO built cmd2 without setuptools_scm[2], also needed a commit
to enable dependency generator[3] which was missed in [2].


[1] https://github.com/openstack/cliff/commit/fe7475d6
[2] https://github.com/rdo-common/python-cmd2/commit/6b677a8
[3] https://github.com/rdo-common/python-cmd2/commit/9520b23

Change-Id: Ia491d5807dc5f770d755f096ec6e54e9dffbd3e1

redhat-openstack/rdoinfo