Add keystone oidc tests

This adds tests to test getting a token (scoped and unscoped) when
keystone is configured to use oidc for authentication.  The oidc
provider is keycloak.  This is based in very large part on Kristi's
work in [1] and [2].

[1] https://github.com/knikolla/devstack-plugin-oidc
[2] https://github.com/CCI-MOC/onboarding-tools

Co-Authored-By: David Wilde <dwilde@redhat.com>
Change-Id: I1772b65f1cc3830ac293a800a79d044a6ab69d65
diff --git a/requirements.txt b/requirements.txt
index 790e605..67f303d 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -5,6 +5,7 @@
 pbr!=2.1.0,>=2.0.0 # Apache-2.0
 
 # xml parsing
+keystoneauth1>=5.1.1 # Apache-2.0
 lxml!=3.7.0,>=3.4.1 # BSD
 tempest>=17.1.0 # Apache-2.0
 oslo.config>=5.2.0 # Apache-2.0