Automatically convert Iterators

[bblommers]

If we pass in an iterator to the match_object-method, it is converted to an empty dictionary during serialization.

It would make more sense if we explicitly converted this to a list instead.

x: Iterator = some_method_returning an iterator()

snapshot.match_object("list_of_objects", x)

The current workaround is to always explicitly convert to a list, but it would be nicer (and less error-prone) if this library handles it for us.

x: Iterator = some_method_returning an iterator()

snapshot.match_object("list_of_objects", list(x))