This looks like a network error to me. An EOF would signal an unexpected end of stream in the HTTP response body, from Github, which should return a valid JSON document. Why would Github return an empty body or broken stream? The only explanation I can think of is some sort of network issue that is preventing the API request from reaching Github, and is instead returning an empty body or breaking the response stream. There are no known issues with Drone, which is quite mature and widely used.
Istio as default blocks all outbound communication with services outside the cluster. So to fix it you should add a ServiceEntry. In my case I’m using drone with Bitbucket. The host you need to add is “*.bitbucket.org”