Switch to the (non-deprecated) registration3 endpoint for nuget
Switch to the (non-deprecated) registration3 endpoint for nuget

nuget stopped updating registration1 a few months ago, we should
use registration3. It looks like everything we read out of the json
works just fine and it was already handling following the pages

librariesio/libraries.io,librariesio/libraries.io,librariesio/libraries.io,librariesio/libraries.io