Native Memory Leak on Android

[JorbeTracy]

Thank you for this helpful project :), I encountered some issues while using it: I used SileroVad for real-time voice activity detection and noticed that the native memory usage kept increasing. I found that some resources might not be released properly:

1. After using getInputTensors to obtain OnnxTensor, the close method was not called to release the resources.
2. The result of session.run was not closed after usage.
3. When using getModel to access the assets stream, the stream was not explicitly closed. It might be better to cache the byte data instead of loading the model repeatedly.

[gkonovalov]

Feel free to create pull request with patch against dev repo and I will merge it.