Remove unused imports

Mechanically remove unused imports with:

    ruff check --select F401 --fix --extend-exclude grpc_protobuf

apps/auracast.py

@@ -23,7 +23,6 @@ import contextlib
 import dataclasses
 import functools
 import logging
-import struct
 from typing import Any, AsyncGenerator, Coroutine, Optional
 
 import click