Replace anyhow with thiserror

[AkiyukiOkayasu]

No description provided.

[AkiyukiOkayasu]

The anyhow crate works with no_std, but not with no_alloc. As pointed out in the #49, this is a significant issue for using it in an embedded environment. This PR is a proof of concept to make error handling work with no_alloc.
thiserror does not work with no_std at the moment. The error_in_core feature will stabilize in Rust 1.81, and it is hoped that it will also work with no_std.
dtolnay/thiserror#304

Currently, a forked version of thiserror is being used.