[typing] Remove overload from inject_client

The decorator can't accept a regular callable (it uses `await` when
calling the wrapped function), and has so far never been used on
anything but coroutines.

src/prefect/client/utilities.py

@@ -7,7 +7,7 @@
 
 from collections.abc import Awaitable, Coroutine
 from functools import wraps
-from typing import TYPE_CHECKING, Any, Callable, Optional, Union, overload
+from typing import TYPE_CHECKING, Any, Callable, Optional, Union
 
 from typing_extensions import Concatenate, ParamSpec, TypeGuard, TypeVar
 
@@ -71,23 +71,9 @@ async def wrapper(*args: P.args, **kwargs: P.kwargs) -> R:
     return wrapper
 
 
-@overload
 def inject_client(
     fn: Callable[P, Coroutine[Any, Any, R]],
 ) -> Callable[P, Coroutine[Any, Any, R]]:
-    ...
-
-
-@overload
-def inject_client(
-    fn: Callable[P, R],
-) -> Callable[P, R]:
-    ...
-
-
-def inject_client(
-    fn: Callable[P, Union[Coroutine[Any, Any, R], R]],
-) -> Callable[P, Union[Coroutine[Any, Any, R], R]]:
     """
     Simple helper to provide a context managed client to an asynchronous function.