input: Write a python function to remove duplicate keys from a dictionary using set.
  assert remove_duplicate_keys({'a': 1, 'b': 2, 'a': 3}) == {'a': 3, 'b': 2}
  assert remove_duplicate_keys({'x': 5, 'y': 5, 'x': 7, 'z': 8}) == {'x': 7, 'y': 5, 'z': 8}
  assert remove_duplicate_keys({'k': 9, 'm': 0, 'k': 4}) == {'k': 4, 'm': 0}
output: def remove_duplicate_keys(d):
      return {k: v for k, v in sorted(d.items(), key=lambda item: item[0])}