sev-6.0.0

What's Changed
This release adds support for multiple attestation report versions.
It also removes the bincode dependency for serializing and deserializing attestation reports. Instead, we now use our own custom binary parser.
Additionally, this release includes new unit tests and various fixes from the official SEV-SNP kernel release.

Notable Changes:
Added the KeyInfo field to the attestation report by @DGonzalezVillal in #259
Updated 0x3 platform initialization data in firmware/SNP by @tylerfanelli in #265
Added attestation report verification using only a certificate by @DGonzalezVillal in #266
Added additional unit tests by @larrydewey in #275
Implemented attestation report versioning updates by @DGonzalezVillal in #268
Full Changelog: v5.0.0...v6.0.0