Add an input for passing additional arguments to cargo audit call

[RadicalZephyr]

As mentioned in #132 it would be useful to be able to pass extra command-line arguments to the cargo audit invocation.

I tried to model the changes on the way that the args input is handled in actions-rs/cargo. This is my first time using typescript however so please let me know if I'm doing anything suboptimal.

Happy to make any changes requested.

Fixes #132.

[RadicalZephyr]

Hey @svartalf could you take a look at this when you get a chance? I'd love to be able to use this feature in the audit check for tokio.