Update docsearch dropdown version

[tesseralis]

As seen in this thread, currently the dropdown, it's hard to search for actual page titles. For example, searching for "Getting Sta" doesn't give a clear indication that "Getting Started" is being selected:

The new version of the dropdown UI makes this clearer:

[uc-deepak]

Hi, how to implement this new search UI?

[alexkrolick]

The algolia search plugin needs an update I believe @uc-deepak