Update der to 0.8

[jonathan-g-davis]

Maintenance task description

The der crate is a core dependency in ANISE for handling ASN.1 DER encoding and decoding. Updating to version 0.8 introduces support for custom error types in deserialization, allowing for more precise error reporting and better integration with ANISE’s error handling system.

Scope of work

• Update the der dependency to 0.8

Priority

Low

• Version 0.8 is not yet stable, so this should only be performed when the dependency is stabilized.