Exposing error in form of thiserror instead of anyhow

[iamsiddhant05]

Is your feature request related to a problem? Please describe.
The error trait is not exposed in the library, which makes it difficult to unwrap and bubble up.

Describe alternatives you've considered
An alternate would be if you could expose a custom RustS3Error trait for error handling

[blackghost1987]

Yeah, this was a bit surprising for me! The anyhow crate explicitly states that it should be used for application code and libraries should use thiserror instead.
Also my upstream library is using thiserror as well, but because of this crate I had to import anyhow as well, just so I could encapsulate it with thiserror.

This looks like a good first contribution, I'll see if I'll have the time to work on a PR.

[nightmared]

In the past, I already tried to add this to rust-s3: #166. Maybe this could serve as a useful basis if you desire to implement it and want to get it merged (something I failed to do, given that my PR was closed without explanations?).
In any case, I second the fact that this would be a very useful feature!

[nightmared]

Sorry, wrong link, the most recent PR on the matter is #189.