optimize users's crud.py database queries

[movassaghi6]

This update includes multiple improvements to the crud.py file for the User table:

1. Optimized get_users_number function by querying the indexed username field, improving performance when counting users.
2. Refactored get_users_with_pagination function to combine user retrieval and birthdate formatting using a list comprehension for cleaner code and enhanced performance.
3. Refactored get_user_if_contains_username function to use a list comprehension for formatting birthdates, leading to cleaner code and potential performance gains.
4. Refactored edit_user function to dynamically update user fields using a dictionary and setattr, reducing multiple if statements and improving maintainability.