Make plt.style.use accept path-like objects in addition to string

plt.style.use(style) accepts a str, dict, or list. The str can be either the name of a style or a path/URL to a style file. I propose that this also accept a pathlike object (pathlib.Path) so that it is unneccesary to cast it like plt.style.use(str(my_path)), but accept it like this plt.style.use(my_path).

There may be other places in the code that accepts file paths as strings.