Change pysaml2 comment in test-requrements.txt.
Change pysaml2 comment in test-requrements.txt.

    Even though the ``pysaml2`` library is used for Keystone2Keystone
    functionalities, Keystone will complain about missing dependency right
    after federation extension is enabled.
    Commend in the test-requirements.txt should be updated to reflect the
    situation.

Change-Id: Id4e615905574d5ad3d050bd8077b25f8327419ab

idjaw/keystone,takeshineshiro/keystone,takeshineshiro/keystone,blueboxgroup/keystone,roopali8/keystone,dstanek/keystone,UTSA-ICS/keystone-kerberos,cernops/keystone,vivekdhayaal/keystone,promptworks/keystone,rajalokan/keystone,klmitch/keystone,jumpstarter-io/keystone,ging/keystone,dims/keystone,jumpstarter-io/keystone,promptworks/keystone,mahak/keystone,nuxeh/keystone,jumpstarter-io/keystone,ging/keystone,nuxeh/keystone,ajayaa/keystone,ilay09/keystone,blueboxgroup/keystone,cernops/keystone,mahak/keystone,jamielennox/keystone,MaheshIBM/keystone,dims/keystone,openstack/keystone,ilay09/keystone,vivekdhayaal/keystone,promptworks/keystone,nuxeh/keystone,openstack/keystone,klmitch/keystone,jonnary/keystone,maestro-hybrid-cloud/keystone,maestro-hybrid-cloud/keystone,roopali8/keystone,mahak/keystone,jamielennox/keystone,rajalokan/keystone,himanshu-setia/keystone,dstanek/keystone,ilay09/keystone,rushiagr/keystone,rushiagr/keystone,UTSA-ICS/keystone-kerberos,idjaw/keystone,ajayaa/keystone,jonnary/keystone,openstack/keystone,MaheshIBM/keystone,rajalokan/keystone,himanshu-setia/keystone,rushiagr/keystone,dstanek/keystone,vivekdhayaal/keystone