add use_pr config item in export_model

pdseg/export_model.py

@@ -52,6 +52,7 @@ def parse_args():
 def export_inference_config():
     deploy_cfg = '''DEPLOY:
         USE_GPU : 1
+        USE_PR : 1
         MODEL_PATH : "%s"
         MODEL_FILENAME : "%s"
         PARAMS_FILENAME : "%s"