BaseResource.contained is incorrectly typed and doesn't have None as a default

[kbehlers]

Thank you for the quick response on #7, here is another typing issue.

It seems like the upstream fern/fhir has BaseResource.contained defined correctly as a nullable list of ResourceList

      contained:
        docs: These resources do not have an independent existence apart from the
          resource that contains them - they cannot be identified independently, and
          nor can they have their own independent transaction scope.
        type: optional<list<ResourceList>>

metriport-python seems to have it as Any and no default

    contained: typing.Any = pydantic.Field(
        description="These resources do not have an independent existence apart from the resource that contains them - they cannot be identified independently, and nor can they have their own independent transaction scope."
    )

[kbehlers]

Looks like this may be problematic across any field with ResourceList in the definition.

OperationOutcome.resource and BundleResponse.outcome are others that use ResourceList but end up being typing.Any

Searching with regex has a few off-target hits, but seems to mostly identify the problematic type hints.

(?<!\*\*kwargs: )(?<!str, )(?<!kwargs_with_defaults: )typing\.Any