Add a `triad_check_reassessment_year` function

[wrridgeway]

There's a really easy way to check for given triads and years if that year is a reassessment year for that triad using remainders. It would be nice to have this functionality in the ccao package. Sorry for the not exactly applicable the python code.

((output["year"] % 3 == 0) & (output["triad"] == "North"))
        | ((output["year"] % 3 == 1) & (output["triad"] == "South"))
        | ((output["year"] % 3 == 2) & (output["triad"] == "City"))