Temporal: Exception thrown when rounding Instant using roundingIncrement: 25

```
> inst = Temporal.Instant.from("2001-09-09T01:46:40Z")
Temporal.Instant{}
> inst.round({roundingIncrement: 25, roundingMode: "ceil", smallestUnit: "microsecond"}).toString()
RangeError: Increment out of range.
```

25 is a valid rounding increment for smallestUnit: microseconds (see https://tc39.es/proposal-temporal/#sec-validatetemporalroundingincrement ).