message: Updated setup.py to use protobuf 3.18
diff: @@ -54,7 +54,7 @@ REQUIRED_PACKAGES = [
  # TODO(b/187981032): remove the constraint for 2.0 once the incompatibile
  # issue is resolved.
  'flatbuffers >= 1.12, <2',
  - 'protobuf >= 3.18.0',
  + 'protobuf == 3.18.0',
  'sounddevice >= 0.4.4',
  ] + SETUP_PACKAGES
  