项目名称包含下划线(_)时，恢复训练时提取 history_step 异常

[frankxzw]

/utils/train.py line: 58

checkpoint_name = checkpoint.split(".")[0].split("_")
if int(checkpoint_name[3]) > history_step:
    newer_checkpoint = checkpoint
    history_step = int(checkpoint_name[3])

to

checkpoint_name = checkpoint.split(".")[0].split("_")
if int(checkpoint_name[-1]) > history_step:
    newer_checkpoint = checkpoint
    history_step = int(checkpoint_name[-1])