solve the bug of training mdtc_bs16_fp32

fix the filepath bug

examples/hey_snips/kws0/conf/mdtc.yaml

@@ -3,7 +3,7 @@
 #                   Data                  #
 ###########################################
 dataset: 'paddlespeech.audio.datasets:HeySnips'
-data_dir: '/PATH/TO/DATA/hey_snips_research_6k_en_train_eval_clean_ter'
+data_dir: '../tests/hey_snips_research_6k_en_train_eval_clean_ter'
 
 ############################################
 #           Network Architecture           #
@@ -46,4 +46,4 @@ num_workers: 16
 checkpoint: './checkpoint/epoch_100/model.pdparams'
 score_file: './scores.txt'
 stats_file: './stats.0.txt'
-img_file: './det.png'
+img_file: './det.png'