I realised that the code is fine it needed just to re-run to work.
Yes I used a new class of Subset that I found in the solutions here subset 4
Unfortunatly I got another issue this time with this loop

for i_fold, (train_idx, valid_idx) in enumerate(folds.split(dsets)):
…
trainloader = torch.utils.data.DataLoader( train, batch_size = batch_size, shuffle =True)
for epoch in range(N_EPOCHS):
for i, data in enumerate(trainloader , 0):
# get the inputs
inputs, labels = data

with the error
AssertionError: force_apply must have bool or int type
if you have a clue on why this accures
thanks you for your response