Fix type annotation

Python3.6 does not allow 'list' as type annotation

Bug: None
Test: local
Change-Id: Ie911b8cfdf1480c30c06bb373182c37aab5d2c56
diff --git a/acts/framework/acts/controllers/fuchsia_lib/package_server.py b/acts/framework/acts/controllers/fuchsia_lib/package_server.py
index 15d743a..96fe901 100644
--- a/acts/framework/acts/controllers/fuchsia_lib/package_server.py
+++ b/acts/framework/acts/controllers/fuchsia_lib/package_server.py
@@ -23,7 +23,7 @@
 from dataclasses import dataclass
 from datetime import datetime
 from io import FileIO
-from typing import Optional
+from typing import List, Optional
 
 from acts import context
 from acts import logger
@@ -53,7 +53,7 @@
     preferred_source: Optional[str]
 
 
-def find_routes_to(dest_ip) -> list[Route]:
+def find_routes_to(dest_ip) -> List[Route]:
     """Find the routes used to reach a destination.
 
     Look through the routing table for the routes that would be used without