Replace RESTStream.get_next_page_token with RESTStream.get_new_paginator

[ericboucher]

We started getting the following warnings:

RESTStream.get_next_page_tokenis deprecated and will not be used in a future version of the Meltano Singer SDK. OverrideRESTStream.get_new_paginator` instead

[laurentS]

Docs: https://sdk.meltano.com/en/latest/guides/pagination-classes.html