replaced model.apply with predict_batch in the optimization loop

pyforecaster/forecasting_models/neural_forecasters.py

@@ -579,7 +579,7 @@ def optimize(self, inputs, objective, n_iter=200, rel_tol=1e-4, recompile_obj=Tr
         normalized_inputs, _ = self.get_normalized_inputs(inputs)
         x, y = normalized_inputs
         def _objective(y, x, **objective_kwargs):
-            return objective(self.model.apply(self.pars, x, y), y, **objective_kwargs)
+            return objective(self.predict_batch(self.pars, [x, y]), y, **objective_kwargs)
 
         # if the objective changes from one call to another, you need to recompile it. Slower but necessary
         if recompile_obj: