Add field for `Components.modelCard.parentModel`

**Proposal**
Separate from base models, models can have a long linage or multiple parent models. The practitioners we spoke with thought it would be helpful to allow listing one or more parent models for a given model, that may be separate from the base model.

**Details**
FieldName: Components.modelCard.parentModel
FieldType: Array. Each list item is a parent model. Contains sub-fields Name, Version, and Source.
Required: No

**Example snippet**

```json
"modelCard" : [
"parentModel": {
[
"name": "Stable-diffusion-xlarge",
"version": "1.1",
"source": "https://huggingface.co/models/stable-diffusion-xlarge1.1"
],
[
"name": "daniels-custom-model",
"version": "2",
"source": "https://huggingface.co/models/daniels-custom-model-v2"
]
}
]
```