Update main.py

[smy999]

No description provided.

[estevaofon]

Hey, thank you very much for the pull requests! I'm not able to test your changes cause is missing somethings. In the main you import those two new characters:

from characters import Blue_Bird
from characters import Big_Bird

But you haven't implemented them.
I also need the images files you address to like in:

bluebird = pygame.image.load(
    "../resources/images/blue-bird3.png").convert_alpha()

In the polygon ice I also need the images files to run the script:

ice = pygame.image.load("../resources/images/ice.png").convert_alpha()
ice2 = pygame.image.load("../resources/images/ice2.png").convert_alpha()