Fix UnionType ImportError

Author: luolingchun

flask_openapi3/request.py

@@ -3,8 +3,13 @@
 # @Time    : 2022/4/1 16:54
 import json
 from json import JSONDecodeError
-from types import UnionType
-from typing import Any, Type, Optional, Dict, get_origin, get_args, Union, TypeVar
+
+from typing import Any, Type, Optional, Dict, get_origin, get_args, Union
+
+try:
+    from types import UnionType  # Python 3.10+
+except ImportError:
+    UnionType = type(Union)
 
 from flask import request, current_app, abort
 from pydantic import ValidationError, BaseModel, RootModel