input: Write a python function to count the number of string values in a dictionary.
  assert count_string_values({"name": "John Smith", "age": 30, "gender": "Male", "is_married": True}) == 2
  assert count_string_values({"name": "Alice", "city": "Wonderland", "age": 29, "occupation": "Adventurer"}) == 3
  assert count_string_values({"name": "Bob", "height": 180, "weight": 75, "employed": False}) == 1
output: def count_string_values(d):
      return sum(1 for value in d.values() if isinstance(value, str))