Use latest version of sphinx-hoverxref

Hi, I work at @readthedocs, and I notice that this project is using an old version of the hoverxref extension https://github.com/tweepy/tweepy/blob/91a41c6e1c955d278c370d51d5cf43b05f7cd979/setup.py#L50

That version is making use of a deprecated API (https://github.com/readthedocs/readthedocs.org/issues/10677), you should be able to upgrade to the latest version (1.4.2) without any changes (I didn't see any breaking changes in your conf.py file).