v3.0.0

• Added inputs.certificate-id for use when using non-Apple signing certs
• Added inputs.signtool to explicitly use a particular tool but not usage is not recommended
• Dropped support for linux, it never really worked and wasn't ever needed, it now errors on Linux
• Improved inputs.file to correctly handle relative and absolute paths
• Refactored code to be more pluggable in the event we want to support additional future signing methods