Better format and static type Pickable Audio

[mubinulhaque]

In accordance with style guide given here:

• Remove space between variable names and colons
• Replace exclamation mark with not keyword
• Add static typing to functions _on_body_entered() and _on_body_exited()
• Add square brackets around class types

Disclaimer

No generative AI was used to enhance or create the code given here.

[BastiaanOlij]

There seem to be some trailing spaces issues on some of the lines. If you wouldn't mind removing those, I can merge this :)

[mubinulhaque]

It should be fixed now.