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Depend on cubicweb >= 3.24

Explicitely exclude debian/ and cubicweb-prov.spec and include
test/data/bootstrap_cubes (required to run tests).

As rules are applying to relation *type*, we're not sure in the prov cube that all
of them are instantiated (i.e. have one or more relation *definition*). This may lead
to undesired warnings on startup if we add them without check the relation is actually
in the schema.

Checking the relation is in the schema requires moving definition to registration
callback.

follow failed attempt in 1bc3f49aedd2

this will ease overriding in e.g. saem_ref.

This entity type should not be provided by the prov cube but rather by client
cube may want to implement Agent or use another type of entities for them (eg
CWUser).

Along the way, drop the `associated_for` computed relation that won't work without
concret implementation of the `associated_with` relation.