If you don't use github actively, everyone is free to get in touch via jobs@divio.ch - in that case, attach something else to show you are qualified :)
I can't count how many times I've seen posts on www.reddit.com/r/cscareerquestions asking about being ready for a job after graduating or saying they feel like a fraud. If somebody did have imposter syndrome and saw that, it would most likely re-affirm their feelings. Especially after seeing the scores of others on the leader board.