return NotImplemented not handled

[AA-Turner]

When running on a single-module exemplar project, pyrefly complains that:

ERROR python\roman_numerals\__init__.py:99:16-30: Returned type `_NotImplementedType` is not assignable to declared return type `bool`
ERROR python\roman_numerals\__init__.py:105:16-30: Returned type `_NotImplementedType` is not assignable to declared return type `bool`

The relevant code is:

    def __eq__(self, other: object) -> bool:
        """Return self == other."""
        if isinstance(other, RomanNumeral):
            return self._value == other._value
        return NotImplemented

    def __lt__(self, other: object) -> bool:
        """Return self < other."""
        if isinstance(other, RomanNumeral):
            return self._value < other._value
        return NotImplemented

[yangdanny97]

Thanks for the report, I added it to the checklist here: #16