Address date-fns warning for year formatting

[sergei-maertens]

In

utrecht/packages/components-react/calendar-react/src/index.tsx

Line 147 in d75de8b

{format(visibleMonth, 'LLLL y', { locale })}

we deliberately use the y formatter rather than Y (see b912501), but date-fns emits a warning about that linking to https://github.com/date-fns/date-fns/blob/main/docs/unicodeTokens.md#popular-mistakes

The solution here seems to be to add the useAdditionalWeekYearTokens: true, option that signals we do in fact mean y rather than Y.