put exception handler around google get_tts_audio call

[sentry-io]

Sentry Issue: CLOUD-LANGUAGE-TOOLS-P

_InactiveRpcError: <_InactiveRpcError of RPC that terminated with:
	status = StatusCode.INVALID_ARGUMENT
	details = "Request contains an invalid argument."
	debug_error_string = "{"created":"@1629963940.803937565","description":"Error received from peer ipv4:142.250.176.202:443","file":"src/core/lib/surface/call.cc","file_line":1069,"grpc_message":"Request contains an invalid argument.","grpc_status":3}"
>
  File "/usr/local/lib/python3.8/dist-packages/google/api_core/grpc_helpers.py", line 66, in error_remapped_callable
    return callable_(*args, **kwargs)
  File "grpc/_channel.py", line 946, in __call__
    return _end_unary_response_blocking(state, call, False, None)
  File "grpc/_channel.py", line 849, in _end_unary_response_blocking
    raise _InactiveRpcError(state)

InvalidArgument: 400 Request contains an invalid argument.
(11 additional frame(s) were not displayed)
...
  File "/usr/local/lib/python3.8/dist-packages/google/cloud/texttospeech_v1/services/text_to_speech/client.py", line 488, in synthesize_speech
    response = rpc(request, retry=retry, timeout=timeout, metadata=metadata,)
  File "/usr/local/lib/python3.8/dist-packages/google/api_core/gapic_v1/method.py", line 142, in __call__
    return wrapped_func(*args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/google/api_core/retry.py", line 283, in retry_wrapped_func
    return retry_target(
  File "/usr/local/lib/python3.8/dist-packages/google/api_core/retry.py", line 190, in retry_target
    return target()
  File "/usr/local/lib/python3.8/dist-packages/google/api_core/grpc_helpers.py", line 68, in error_remapped_callable
    raise exceptions.from_grpc_error(exc) from exc