CS50P Week 4 psets "Guessing Game" and "Bitcoin Price Index" fail to exit if using main() function without if __name__ footer

The check50 for game.py runs into a timeout error if the user provided a `main()` function but did not include the `if __name__ == "__main__":` block before the `main()` call. Functions that run at the base level without defining `main()` can pass check50 without problems.

I think this should be noted in the pset page to avoid confusion.