[GAN] #5 Refactor Magic Numbers: Replace Magic Numbers with Constants

[veeradi34]

Description: There are several magic numbers used throughout the code (e.g., 28, 32, 8). These should be replaced with named constants for better readability and maintainability.

Tasks:
Identify magic numbers in the code.
Create constants at the top of the file (e.g., IMAGE_SIZE = 28) and use them in the code.