Improve error printing

[kylebarron]

I was talking with @vincentsarago and he mentioned he got an error that looked like:

GenericError: Generic {
    store: "S3",
    source: BareRedirect,
}

Looking at the upstream implementation I see

/// Retry request error
#[derive(Debug, thiserror::Error)]
pub enum Error {
    #[error("Received redirect without LOCATION, this normally indicates an incorrectly configured region")]
    BareRedirect,

Perhaps we should update our errors to use the to_string impl? Note that this was previously changed in #54 https://github.com/developmentseed/obstore/blame/78860c6e71255bdf06c973b9b9435cdedc2e3fdd/pyo3-object_store/src/error.rs#L112