input: Write a python function to remove a specified character from a string.
  assert remove_character("hello world", "o") == "hell wrld"
  assert remove_character("banana", "a") == "bnn"
  assert remove_character("mississippi", "s") == "miiippi"
output: def remove_character(s: str, char: str) -> str:
      return s.replace(char, '')