input: Write a python function to remove a specific character from a given string.
  assert remove_char("hello world", "o") == "hell wrld"
  assert remove_char("test string", "t") == "es sring"
  assert remove_char("example", "e") == "xampl"
output: def remove_char(s: str, char: str) -> str:
      return s.replace(char, "")