update translation for asyncio policy system is deprecated

Author: Tommy0901

library/asyncio-eventloop.po

@@ -127,6 +127,8 @@ msgid ""
 "event loop if present else it will return the loop set by :func:"
 "`set_event_loop`."
 msgstr ""
+":mod:`!asyncio` 的系統政策已被棄用，並將於 Python 3.16 中移除；此後，此函式將返回當前執行中的事件"
+"迴圈（若存在），否則將返回由 :func:`set_event_loop` 設定的迴圈。"
 
 #: ../../library/asyncio-eventloop.rst:74
 msgid "Set *loop* as the current event loop for the current OS thread."