AC: fix mappilary converter (#3006)

Author: eaidova

tools/accuracy_checker/openvino/tools/accuracy_checker/annotation_converters/mapillary_20.py

@@ -102,7 +102,7 @@ def convert(self, *args, **kwargs):
             annotation = SegmentationAnnotation(file_in_dir.name, file_in_dir.name, mask_loader=GTMaskLoader.PILLOW)
             annotations.append(annotation)
 
-        return ConverterReturn(annotations, None)
+        return ConverterReturn(annotations, self.get_meta(), None)
 
     def get_meta(self):
         return {'label_map': self.label_map}