The github project description:

Simple HTTP and REST client library for Go (inspired by Ruby rest-client)

I didn't know what "Go" was. Here's what it is: "Go is a programming language built to resemble a simplified version of the C programming language. It compiles at the machine level. Go was created at Google in 2007." This is the full user-agent:

go-resty/2.12.0 (https://github.com/go-resty/resty)

The hit came from 192.186.57.20, it asked for my landing page, nothing else. It's part of AS132721 (FEDERAL ONLINE GROUP LLC) which has 13k IP's, split between "federal online group" (supposedly located Westlake Village California) and Hong Kong. I have no previous hits from that AS, now blocking it.