I’m seeing the same thing here, can’t see what we are doing wrong as nothing has changed on our side. I have contacted them to find out what is going on.
Got a response back from github in record time (minutes!). They changed something on their end (undocumented) to block certain people (not us) that were misusing their api. We were just collateral damage. I have made a change to our code as suggested by github and it’s working again, we’ll have an update out later today with the fix.