Add castellan to LIBS_FROM_GIT

Allow castellan to be installed from git instead of pip.

Castellan has recently been moved under the oslo framework,
and the barbican-tempest-plugin tests which use castellan
would benefit from the ability to usd castellan from git
instead of pip.

Change-Id: I96edca90c61aec84637b7b1ce842eff04c521923
diff --git a/tests/test_libs_from_pypi.sh b/tests/test_libs_from_pypi.sh
index 3d4bcd2..314a9d5 100755
--- a/tests/test_libs_from_pypi.sh
+++ b/tests/test_libs_from_pypi.sh
@@ -43,6 +43,7 @@
 ALL_LIBS+=" oslo.cache oslo.reports osprofiler"
 ALL_LIBS+=" keystoneauth ironic-lib neutron-lib oslo.privsep"
 ALL_LIBS+=" diskimage-builder os-vif python-brick-cinderclient-ext"
+ALL_LIBS+=" castellan"
 
 # Generate the above list with
 # echo ${!GITREPO[@]}