Feature summary:
Make pagegenerators.PetScanPageGeneratora collections.Generator

Use case(s):
Currenly pagegenerators.PetScanPageGenerator is an Iterable; it works with for loops but it doest not support next() function. To convert it to an Iterator the iter() function must be used.

See also T312654

Benefits:
Making pagegenerators.PetScanPageGenerator a collections.abc.Generator it is capable to be used as

Iterable (for loops etc.)
Iterator (next() function etc.)
Generator (close() method which is used by BaseBot; BaseBot tries to convert every Iterable to a Generator)