Update grpcio async ServerInterceptor test case for Optional return

Author: Rhadamanthus1

stubs/grpcio/@tests/test_cases/check_server_interceptor.py

@@ -26,9 +26,9 @@ def intercept_service(
 class NoopAioInterceptor(grpc.aio.ServerInterceptor):
     async def intercept_service(
         self,
-        continuation: Callable[[grpc.HandlerCallDetails], Awaitable[grpc.RpcMethodHandler[RequestT, ResponseT]]],
+        continuation: Callable[[grpc.HandlerCallDetails], Awaitable[grpc.RpcMethodHandler[RequestT, ResponseT] | None]],
         handler_call_details: grpc.HandlerCallDetails,
-    ) -> grpc.RpcMethodHandler[RequestT, ResponseT]:
+    ) -> grpc.RpcMethodHandler[RequestT, ResponseT] | None:
         return await continuation(handler_call_details)