Bump openstack-placement version in functional tox env

Nova functional tests import the placement test fixture
and which require the new fix change merged in placement
- https://review.opendev.org/c/openstack/placement/+/869525

the above change is released in openstack-placement 9.0.0.0b1
version
- https://review.opendev.org/c/openstack/releases/+/870989

bumping that version in tox.ini as functional test env use
the placement from PyPi.

Change-Id: Ib0217f85f9d2782f1a742b19f6ec56a082946a2b

Author: Ghanshyam Mann

tox.ini

@@ -61,7 +61,7 @@ description =
 # because we do not want placement present during unit tests.
 deps =
   {[testenv]deps}
-  openstack-placement>=1.0.0
+  openstack-placement>=9.0.0.0b1
 extras =
 commands =
   stestr --test-path=./nova/tests/functional run {posargs}