input: Write a python function to validate a password based on given criteria.
  assert validate_password("Password1")==True
  assert validate_password("password1")==False
  assert validate_password("Password")==False
  assert validate_password("Pass1")==False
output: def validate_password(password):
      if len(password) < 8:
          return False
      has_upper = any(char.isupper() for char in password)
      has_lower = any(char.islower() for char in password)
      has_digit = any(char.isdigit() for char in password)
      return has_upper and has_lower and has_digit