Apply suggestion from @Copilot

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: HydrogenSulfate

ppsci/solver/train.py

@@ -257,7 +257,6 @@ def train_LBFGS_epoch_func(solver: "solver.Solver", epoch_id: int, log_freq: int
                         gc.collect()
                     _constraint.data_iter = iter(_constraint.data_loader)
                 input_dict, label_dict, weight_dict = next(_constraint.data_iter)
-
             reader_cost += time.perf_counter() - reader_tic
 
             for v in input_dict.values():