fix: timetable week problem

[ivanfei-1]

Move the courses on Sundays a week forward to match the school schedule.
Close #217.

[w568w]

Could there be a chance that a Course is on both Sunday and Monday?

Say, course A is on Week 1's Sun. & Mon. (i.e. 2/19 & 2/20) in this term. Under your any() assertion, it will be add to both Week 0 and 1 (i.e. 2/13, 2/19, 2/20 and 2/26).

Consider moving assessments like course.times!.any((element) => element.weekDay != 6)) into the inner for loop.

[w568w]

As above.

[ivanfei-1]

Fixed.