update pydantic encoder

Author: Matt Sokoloff

labelbox/data/serialization/coco/converter.py

@@ -1,11 +1,16 @@
 from typing import Dict, Any, Union
-from pathlib import Path
+from pathlib import Path, PosixPath, WindowsPath
 import os
 
+import pydantic.json
+
 from labelbox.data.annotation_types.collection import LabelCollection, LabelGenerator
 from labelbox.data.serialization.coco.instance_dataset import CocoInstanceDataset
 from labelbox.data.serialization.coco.panoptic_dataset import CocoPanopticDataset
 
+pydantic.json.ENCODERS_BY_TYPE[PosixPath] = str
+pydantic.json.ENCODERS_BY_TYPE[WindowsPath] = str
+
 
 def create_path_if_not_exists(path: Union[Path, str],
                               ignore_existing_data=False):