Type mismatch in `_navigator.search_authors()`

[YoungMind1]

search_authors() return type should be either Generator[Author, None, None] or Iterator[Author]; currently it is Author.

[YoungMind1]

I couldn't setup a proper python3.8 env in order to fully test. I think Generator[Author, None, None] should do the trick for python3.8, in python 3.9 and later [Author] should suffice.