Bug fix and maintenance release

Maintenance release - update dependencies and sign Mac OSX binary

Feature release - add support for OSX Arm 64

Feature release - add CycloneDX v1.4 support

Feature release - support conversion to/from SPDX v2.2 JSON

Upgrade to .NET 6

Feature release - key generation, signing and verification

Feature release - `add files` command

Maintenance release

Bugfix release - include merged BOM subject and dependency refs