fix: change device spec separator from colon to pipe

[roderickvd]

Description

Using a colon as separator in device specifications conflicted with ALSA device names that contain colons. Changed to pipe character which is less likely to appear in device names across platforms (Linux/ALSA, macOS/CoreAudio, Windows/WASAPI).

Related Issues

Fixes #33

Testing

Tested on macOS Ventura & Debian Bookworm.

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[roderickvd]

I'm gonna go ahead and merge this immediately. I've been able to reproduce and fix the bug with this.