Implement `core::error::Error` for error types

[PhilippGackstatter]

Would you accept a PR or consider implementing core::error::Error for error types like EncodeError and DecodeError, now that the Error trait is available in core? This would allow no_std crates to wrap the error types as source errors into a Box<dyn Error> for example.

Thank you!

[apoelstra]

The MSRV of this project is 1.63.0 so unfortunately we can't do this here.

[PhilippGackstatter]

I see, thanks for the quick answer. I guess changing the MSRV depends on other dependent projects also increasing theirs which makes this tricky?

[apoelstra]

Yes. Changing the MSRV would force downstream users to replace their compiler toolchain to one that isn't available in Debian, is a huge pain to build independently, which has potentially different behavior, and hasn't even existed for that long.