amend bootstrap algorithm to support more than just daily predictions

At the moment, there is a check on the length of each year block, but there is an assumption that predictions are daily:

// check that year is complete (without a rigorous leap year check)
int n_days = xt::sum(wdw)();
if ((n_days != 365) && (n_days != 366))
{
    throw std::runtime_error(
        "year starting in " + std::to_string(y - 400)
        + " is incomplete"
    );
}

https://gitlab.irstea.fr/HYCAR-Hydro/evalhyd/evalhyd-cpp/-/blob/805e4a6af9271dec04e55417d7539b7c09841f40/include/evalhyd/detail/uncertainty.hpp#L107-115

This check needs to be made more versatile so that another temporal resolution can be considered, as long as complete years are provided.

added BUG label

mentioned in commit 5df680c4

mentioned in commit d87af253

closed

mentioned in commit a4bc6aa7