Fix license header

bob/paper/ijcb2021_synthetic_dataset/generate/db_generator.py

 # Copyright (c) 2021, Idiap Research Institute. All rights reserved.
 #
-# This work is made available under a Non-Commercial Reserach and Educational Use Only license.
+# This work is made available under a custom license, Non-Commercial Research and Educational Use Only 
 # To view a copy of this license, visit
 # https://gitlab.idiap.ch/bob/bob.paper.ijcb2021_synthetic_dataset/-/blob/master/LICENSE.txt
 import os