SPDX json marshalling fails if author name is left as default in generated config file

[par-anderssonTE]

In the generated template config file, the "author" section looks like this:
author:

• name: '[OPTIONAL]'
  email: '[OPTIONAL]'

However, if you leave this as is, json marshalling fails on assembly:

Error: json: error calling MarshalJSON for type common.Creator: unexpected end of JSON input

Removing the author section or filling in the name solves the issue.

Expected behaviour:
Since sbomasm handles other config file properties with the default placeholder gracefully, it should do the same for author name.

[riteshnoronha]

Thanks for reporting this. Fix has been merged.