[Ch6Nb02] Fixed errors and compatibility issues

1.	Added  “if torch.cuda.is_available()” to check if we are using gpu.
2.	Added a try except block to upload files to colab.
3.	Removed 'fetch data' function as the 'get_data' function was doing the same thing.
4.	Fixed path for windows and colab.
5.	Added a if condition for using 'model.cuda()' only when we are using gpu.

Author: jatinpapreja