sortby parameter is typed as List[str], but value must be List[Dict[str,str]] when doing POST search

[philvarner]

The search sortby parameter is typed as List[str], I assume expecting a GET value like +datetime,-eo:cloud_cover to be passed.
However, when doing POST search, the server must be a list of sort objects, e.g.,

sortby=[
            {
                "field": "properties.eo:cloud_cover",
                "direction": "asc"
            }
        ]

When running this query, the failure message is because it's putting a string value for sortby (or a list?) but then pydantic validation is expecting a dict:

$ stac-client search  https://planetarycomputer.microsoft.com/api/stac/v1 -c sentinel-2-l2a --bbox -72.5 40.5 -72 41 --sortby '+properties.datetime' --method POST
1 validation error for Request
body -> sortby -> 0
  value is not a valid dict (type=type_error.dict)

I think the correct thing to do is for the type to be Union[List[str], List[Dict[str,str]] ], and then have a dynamic check for the type in the list depending on if GET or POST is being used.