Add Date to minimum and maximum in too small/big issues

[gebsh]

Fixes #5350.

[colinhacks]

Unfortunately this would break any code that's expecting these values to be some kind of numeric value. I think the better solution would be to convert the Date values to a Unix timestamp here. I'm pretty sure the reason I omitted Date in the first place was so it would be easier to do error customization for "too_small" and "too_big", and I think I kinda forgot to do the Date -> number conversion 😅

[gebsh]

Oh, okay. That's fine too, I think, since a timestamp can be turned into a Date object by an error map anyway. I'll update this PR later to do the conversion instead.