Update roman_numerals.py

Author: lighting9999

conversions/roman_numerals.py

@@ -63,5 +63,5 @@ def int_to_roman(number: int) -> str:
     return "".join(result)
 
    if __name__ == "__main__":
-       import doctest
-       doctest.testmod()
+    import doctest
+    doctest.testmod()