refactor: Add error trait bound to generic error type

[krokosik]

Thank you for the great library! I would like to improve its error handling by adding the Error trait bound to your error type, so that it is compatible with crates such as anyhow. For example when I use the ? operator in a function that returns an anyhow::Result I have to append map_err to each method call.

[krokosik]

Okay, looks like my amateur Rust knowledge showed off ;//

It seems that the core::error::Error trait exists since 1.81.0 and I'm not sure how to work around that to get anyhow compat