fix(type-safe-api): deserialize python body with model_validate inste…

…ad of from_json (#686)

A bug in OpenAPI Generator can cause some fields to be omitted when deserializing python models
which make use of `allOf` to compose schemas:

OpenAPITools/openapi-generator#12778

Instead of using the generated `from_json` method which may omit fields to deserialize, we use the
pydantic `model_validate` method directly.

packages/type-safe-api/scripts/type-safe-api/generators/python/templates/operationConfig.mustache

@@ -71,7 +71,7 @@ def parse_body(body, content_types, model):
     """
     if len([c for c in content_types if c != 'application/json']) == 0:
         if model != Any:
-            body = model.from_json(body)
+            body = model.model_validate(json.loads(body))
         else:
             body = json.loads(body or '{}')
     return body