Let's say that there were 3 time points. If the time points are always going ot be the same, the data could be:
patient time_1 time_2 time_3 y
1 1.2 7.5 11.0 0.1
2 5.4 3.1 1.0 1.9
...
If that were the case you can resample as usual since 1 row = 1 independent unit.
If the time points vary, then you would need something like
patient time x y
1 1 1.1 6.1
1 7 5.6 1.7
1 9 9.3 1.0
2 1 0.3 3.1
2 4 4.3 6.0
...
In this case, 2+ rows = 1 independent unit so you have to resample by patient using rsample::group_vfold_cv() or some other method.