0.4.2: Implement std::error::Error for cocoon::Error via optional `th…

…iserror` (#28)

This version introduces an optional implementation of
`std::error::Error` for `cocoon::Error` via `thiserror` feature
(optional dependency). See previous commits.

It also bumps the nightly version for test coverage
because of `zeroize` crate's MVRC bump to rustc 1.60.

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "cocoon"
-version = "0.4.1"
+version = "0.4.2"
 
 authors = ["Alexander Fadeev <[email protected]>"]
 categories = ["cryptography", "no-std", "parser-implementations"]