Add v3scopedsaml entry to the setup.cfg.

Since Patch https://review.openstack.org/#/c/107231/ was abandoned and
entry ``v3unscopedsaml`` stays in the setup.cfg, there should
also some room for v3scopedsaml entry which lets users scope their
unscoped tokens.

Change-Id: Ie42206c323d287b905b4c5da9c790e544a8b8433
Merge "Add v3scopedsaml entry to the setup.cfg."