AttributeError: 'array.array' object has no attribute 'tostring'

[diallodavid]

File "/env/lib/python3.9/site-packages/googlesamples/assistant/grpc/audio_helpers.py", line 57, in normalize_audio_buffer
buf = arr.tostring()
AttributeError: 'array.array' object has no attribute 'tostring'

What’s New In Python 3.9
Removed

• array.array: tostring() and fromstring() methods have been removed. They were aliases to tobytes() and frombytes(), deprecated since Python 3.2. (Contributed by Victor Stinner in bpo-38916.)

[Aom92]

Could you merge this? People following Google's Tutorial might get confused when the sample won't work