Fix Python 3.12 aubio import check

[antide-xx]

This fixes a Python 3.12 incompatibility in Panon.

Python 3.12 removed importlib.find_loader(), which caused the backend to fail with:

AttributeError: module 'importlib' has no attribute 'find_loader'

This patch replaces it with importlib.util.find_spec(), restoring backend startup.

Tested on:

• Ubuntu 24.04
• Plasma 5.27
• PipeWire (PulseAudio backend)
• Python 3.12