[test] Pin some test dependencies
We currently have CI failures because cubes used as test dependencies have been
updated to new-style cube layout. To avoid this, pin them to previous released.
Those dependencies should be removed but in the mean time this should be enough
(and backported in all active branches).
mock
psycopg2
ldap3 < 2
cubicweb-basket
cubicweb-card
cubicweb-comment
cubicweb-file
cubicweb-localperms
cubicweb-tag