input: Write a function to convert a binary string to a human-readable string.
  assert binary_to_string("0100100001100101011011000110110001101111") == "Hello"
  assert binary_to_string("010000010100001001000011") == "ABC"
  assert binary_to_string("0110100001101001") == "hi"
output: def binary_to_string(binary_str):
      chars = [binary_str[i:i+8] for i in range(0, len(binary_str), 8)]
      return ''.join([chr(int(char, 2)) for char in chars])