Use Union instead of | for Python 3.9

Author: DouweM

pydantic_ai_slim/pydantic_ai/models/__init__.py

@@ -12,7 +12,7 @@
 from dataclasses import dataclass, field, fields, replace
 from datetime import datetime
 from functools import cache
-from typing import Callable
+from typing import Callable, Union
 
 import httpx
 from typing_extensions import Literal, Self, TypeAliasType
@@ -313,7 +313,9 @@ def update(self, profile: ModelProfile | None) -> Self:
         return replace(self, **shallow_copied_dict)
 
 
-ModelProfileSpec = TypeAliasType('ModelProfileSpec', ModelProfile | Callable[[str], ModelProfile | None] | None)
+ModelProfileSpec = TypeAliasType(
+    'ModelProfileSpec', Union[ModelProfile, Callable[[str], Union[ModelProfile, None]], None]
+)
 
 DEFAULT_PROFILE = ModelProfile()