fix: use running loop in audio helpers

[Ghraven]

Summary

• replace asyncio.get_event_loop() with asyncio.get_running_loop() inside async audio helper methods
• keep the existing callback behavior by retaining the captured running loop for thread-safe callback notifications and executor calls

Problem

asyncio.get_event_loop() is legacy behavior in modern async code and can behave differently depending on thread/policy state. These methods are already executing inside a running coroutine, so the running loop is the precise loop the helper should capture.

Before / after

Before, Microphone.record(), LocalAudioPlayer.play(), and LocalAudioPlayer.play_stream() asked asyncio for the ambient event loop.

After, they capture the currently running loop directly with asyncio.get_running_loop().

Verification

• python -m py_compile src\openai\helpers\microphone.py src\openai\helpers\local_audio_player.py
• git diff --check
• confirmed no remaining get_event_loop() calls in the touched helper files