Replace Mermaid's dependency on `moment` with `dayjs`.
[Moment is now in maintenance mode][1], and they don't recommend
using it.
[Dayjs][2] has almost exactly the same API as moment, and is still
curently being maintained. Unlike moment, dayjs objects are immutable,
which makes our life much easier, but we need to do
`a = a.add(1, "day")` instead of just `a.add(1, "day")`.
We can't use `dayjs.duration`, because unlike `moment.duration`,
[dayjs durations always degrade to ms][3].
This causes issues with daylight savings, since it assumes that each
day is 24 hours, when some days have 23/25 hours with daylight savings.
(it also assumes that each month is 30 days).
However, `dayjs.add(1, "d");` correctly adds 1 days, even when that
day is only 23 hours long, so we can use that instead.
[1]: https://momentjs.com/docs/#/-project-status/
[2]: https://day.js.org/
[3]: https://day.js.org/docs/en/durations/durations
* develop:
chore(docs): Update live editor links
update user story link
feat(gantt): Add option 'tickInterval' for custom tick interval
Convert attr to classed
Convert attr to style
