Fix name typo from prop to props

[guyzyl]

Committer Notes

In all metaschemas, the name props is used to signify the list of metadata properties.
This PR fixes an obvious typo in the assessment results metaschema where the name prop is used instead of props.

This will most likely break backwards compatibility, but since this is an obvious typo/fix I think it is worth considering for versions earlier than v2.0.

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[david-waltermire]

Thanks for the fix!