Remove python-keystoneclient from test-requirements

We don't need it for any purpose.

Change-Id: Ib8e6039fc72f9f813eabf15e8ef7b216215576da
diff --git a/test-requirements.txt b/test-requirements.txt
index b444297..3f82796 100644
--- a/test-requirements.txt
+++ b/test-requirements.txt
@@ -6,7 +6,6 @@
 sphinx>=1.5.1,<1.6
 sphinxcontrib-blockdiag>=1.1.0
 fixtures>=0.3.14
-python-keystoneclient>=0.4.2
 python-subunit
 testrepository>=0.0.17
 testtools>=0.9.32