Try to debug why test.wav is not found.

src/synthesize.py

@@ -79,6 +79,8 @@ def synth_espeakng(text:str, model:str):
         esng.voice = model
         esng.say(text, export_path="test.wav")
         
+        print(["test.wav" in os.listdir()])
+        
         sampling_rate, wav = wavfile.read('test.wav')
         os.remove("test.wav")