v0.10.1

Fix two safety issues in the 0.10 line:

• Bound AVX2 reads in the safe hex_decode_unchecked API by the source length.
• Return only the written prefix from hex_encode and hex_encode_upper, even when the destination has extra capacity.

Restore the Error trait implementation on Rust 1.61 while retaining core::error::Error on newer toolchains. Public signatures and the Rust 1.61 MSRV are unchanged.