fix model name to text_det_model & text_rec_model

paddlex/pipelines/OCR.yaml

@@ -3,7 +3,7 @@ Global:
   input: https://paddle-model-ecology.bj.bcebos.com/paddlex/imgs/demo_image/general_ocr_001.png
   
 Pipeline:
-  det_model: PP-OCRv4_mobile_det
-  rec_model: PP-OCRv4_mobile_rec
-  batch_size: 1
+  text_det_model: PP-OCRv4_mobile_det
+  text_rec_model: PP-OCRv4_mobile_rec
+  text_rec_batch_size: 1
   device: "gpu:0"