fix: fixed validation of parsed llm output

Author: MagdalenaKotynia

src/rai_bench/rai_bench/vlm_benchmark/interfaces.py

@@ -191,8 +191,11 @@ def get_structured_output_from_messages(
                         )
 
                     parsed = validated_message.parsed
-                    if isinstance(parsed, self.structured_output):
-                        return parsed
+                    expected_output_type = self.structured_output
+                    parsed_valid_output = expected_output_type.model_validate(
+                        parsed.model_dump()
+                    )
+                    return parsed_valid_output
                 except ValidationError:
                     continue
         return None