[predicates] keep making `yes` predicate importable from cubicweb (closes #2790319)
The `yes` predicate was moved out in CubicWeb 3.15 but it should have
remained importable from the cubicweb.predicates module, for bw compat
reasons and also because logilab.common.registry is an implementation
detail.
# -*- coding: utf-8 -*-
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s schema"""