Bug fix; NameError: name 'self' is not defined

`self.voice` replaced with `voice` in the ONNX version of inference sample.

README.md

@@ -67,7 +67,7 @@ tokenizer = IPATokenizer()
 inputs = tokenizer("Say something here")
 
 # Get speaker array
-speaker = np.array(self.voices["af"], dtype=np.float32)
+speaker = np.array(voices["af"], dtype=np.float32)
 
 # Generate speech
 outputs = model.run(None, {