bug when using calendar years instead of hydrological years for bootstrap

It is expected that when using the bootstrapping functionality, the user will provide series of complete hydrological years (e.g. period of three years from 2001-10-01 until 2004-09-30 in the northern hemisphere), it is not enforced, and complete calendar years can be provided (e.g. period of three years from 2001-01-01 until 2003-12-31).

However, in practice, there is a bug, because in the first case 2004-2001=3 (so all three years are sampled), but in the second case 2003-2001=2 (so only two years are sampled). This is a special case when the series starts on 1st of January, as soon as the series starts on 2nd of January the problem disappears.

In evalhyd, when using calendar years, it fails an internal check and raises an error (see https://gitlab.irstea.fr/HYCAR-Hydro/evalhyd/evalhyd-cpp/-/blob/86f1e26a5884cdf3548f44fbb33a5e90e15f5257/include/evalhyd/detail/uncertainty.hpp#L112-L119).