Fixed pytype error.

compiler_opt/distributed/worker.py

diff --git a/compiler_opt/distributed/worker.py b/compiler_opt/distributed/worker.py
index 8fee04d..5e28aea 100644
--- a/compiler_opt/distributed/worker.py
+++ b/compiler_opt/distributed/worker.py
@@ -64,7 +64,7 @@
     return e
 
 
-def lift_futures_through_list(future_list: WorkerFuture[List],
+def lift_futures_through_list(future_list: WorkerFuture,
                               expected_size: int) -> List[WorkerFuture]:
   """Convert Future[List] to List[Future]."""
   flattened = [concurrent.futures.Future() for _ in range(expected_size)]