[exceptions] fix string conversion for Unauthorized exception changeset 3cb87b61b067 changed CubicWebException to define __unicode__ as the main entry point for string conversion, but left Unauthorized's __str__ definition unchanged, leading to a mismatch. Closes #10646396.

sync_schema_props_perms('cw_source', syncprops=False)
if schema['BigInt'].eid is None:
    add_entity_type('BigInt')