fix typing issue with UnionType in py3.9

Signed-off-by: Filinto Duran <[email protected]>

Author: filintod

dapr/clients/grpc/_conversation_helpers.py

@@ -18,7 +18,6 @@
 import string
 from dataclasses import fields, is_dataclass
 from enum import Enum
-from types import UnionType
 from typing import (
     Any,
     Callable,
@@ -37,6 +36,12 @@
 
 from dapr.conf import settings
 
+import types
+
+# Make mypy happy. Runtime handle: real class on 3.10+, else None.
+# TODO: Python 3.9 is about to be end-of-life, so we can drop this at some point next year (2026)
+UnionType: Any = getattr(types, 'UnionType', None)
+
 # duplicated from conversation to avoid circular import
 Params = Union[Mapping[str, Any], Sequence[Any], None]
 
@@ -857,7 +862,9 @@ def _coerce_literal(value: Any, lit_args: List[Any]) -> Any:
 
 def _is_union(t) -> bool:
     origin = get_origin(t)
-    return origin in (Union, UnionType)  # handles 3.8–3.13+
+    if origin is Union:
+        return True
+    return UnionType is not None and origin is UnionType
 
 
 def _coerce_and_validate(value: Any, expected_type: Any) -> Any: