NuGet package party types is missing

[pombredanne]

See https://github.com/nexB/scancode-toolkit/issues/2989

parties:
            -   type:
                role: author
                name: Sam Saffron,Marc Gravell,Nick Craver
                email:
                url:
            -   type:
                role: owner
                name: Sam Saffron,Marc Gravell,Nick Craver
                email:
                url:

is missing a party type