Update library/contextvars.po

Author: Dr-XYZ

library/contextvars.po

@@ -69,7 +69,7 @@ msgid ""
 "`ContextVar.get` when no value for the variable is found in the current "
 "context."
 msgstr ""
-"當在目前的情境中找不到變數的值時，:meth:`ContextVar.get` 會回傳僅限關鍵字參"
+"當在目前的情境中找不到變數的值時，:meth:`ContextVar.get` 會回傳可選的僅限關鍵字參"
 "數 *default*。"
 
 #: ../../library/contextvars.rst:42