Update global-requirement for tempest-lib

The latest tempest-lib contains compute service clients.
This patch bumps the version for the latest to use these clients.

Change-Id: I33e9e59f3aaf51666254f5c38eca98a28cb5023c
Depends-on: I855f2d1da34d2f3bd2d1def2eba14590494ebb99
diff --git a/requirements.txt b/requirements.txt
index 17d063d..d470c30 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -22,6 +22,6 @@
 iso8601>=0.1.9
 fixtures>=1.3.1
 testscenarios>=0.4
-tempest-lib>=0.10.0
+tempest-lib>=0.11.0
 PyYAML>=3.1.0
 stevedore>=1.5.0 # Apache-2.0