Release v1.8.8 (#414)

 cmake_minimum_required(VERSION 3.13 FATAL_ERROR)
 project(sherpa-onnx)
 
-set(SHERPA_ONNX_VERSION "1.8.7")
+set(SHERPA_ONNX_VERSION "1.8.8")
 
 # Disable warning about
 #

@@ -266,7 +266,7 @@ def main():
 
     if name == "distil-medium.en":
         filename = "./distil-medium-en-original-model.bin"
-        if not Path(filename):
+        if not Path(filename).is_file():
             raise ValueError(
                 """
                 Please go to https://huggingface.co/distil-whisper/distil-medium.en