Fixed an issue where search_pubs returns an empty response when only a single publication exists for the query.

Fixes #541 #517.

Fixed an issue where you get an empty response when you try to use search_pubs and only a single publication exists for the query. This is because the paper html element has a different class list when only a single publication exists.
Changed the _SearchScholarIterator object to set the total_results equal to the length of _rows. This is because a page in scholar containing a single result doesn't contain a div that says "About n results", from which _get_total_results derives the number of publications.
Added a unit test for this issue.

Checklist

[x] Check that the base branch is set to develop and not main.
[x] Ensure that the documentation will be consistent with the code upon merging.
[x] Add a line or a few lines that check the new features added.
[x] Ensure that unit tests pass. If you don't have a premium proxy, some of the tests will be skipped. The tests that are run should pass without raising MaxTriesExceededException or other exceptions.