getMenstruationForUser(PartialUser user, Instant startTime, @Nullable Instant endTime)
Asynchronously makes a request to the /menstruation endpoint to fetch the menstruation data for the given user.
Parameters:
user - the user to fetch the menstruation data for
startTime - the start time to fetch data since
endTime - then end time to fetch data before
Returns:
future that will contain the API response upon completion