change username

aicrowd.json

 {
   "challenge_id": "aicrowd-neurips-2020-minerl-challenge",
   "grader_id": "aicrowd-neurips-2020-minerl-challenge",
-  "authors": ["PFN.keisuke.nakata"],
+  "authors": ["minerl_rainbow_baseline"],
   "tags": "RL",
   "description": "Test Model for MineRL Challenge",
   "gpu": false