bug in annualized shock decomposition

when removing unused output args in commit 735bd66d, we created a bug in annualized_shock_decomposition. there, the second unised argument is actually necessary to trigger the behavior in plot_shock_decomposition that depends on nargout inline 535 .https://git.dynare.org/Dynare/dynare/-/blob/master/matlab/shock_decomposition/plot_shock_decomposition.m?ref_type=heads#L535

Admittedly, this is a very obscure feature...