Fix property between Role and Person for contributors

[progval]

It should be:

{
    "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
    "type": "SoftwareSourceCode",
    "contributor": [
        {
            "type": "schema:Role",
            "schema:contributor": {
                "type": "Person",
                "givenName": "Jane"
            },
        }
    ]
}

instead of:

{
    "@context": "https://doi.org/10.5063/schema/codemeta-2.0",
    "type": "SoftwareSourceCode",
    "contributor": [
        {
            "type": "schema:Role",
            "schema:author": {
                "type": "Person",
                "givenName": "Jane"
            },
        }
    ]
}

[progval]

@hjonin Looks good?

[hjonin]

Thanks for this fix!