Relax asyncio.TimerHandle.__init__ args parameter (#4193)

Just like the Handle class, the TimerHandle class can take any sequence
here, not just a list.

stdlib/3/asyncio/events.pyi

@@ -29,7 +29,7 @@ class Handle:
         def cancelled(self) -> bool: ...
 
 class TimerHandle(Handle):
-    def __init__(self, when: float, callback: Callable[..., Any], args: List[Any],
+    def __init__(self, when: float, callback: Callable[..., Any], args: Sequence[Any],
                  loop: AbstractEventLoop) -> None: ...
     def __hash__(self) -> int: ...
     if sys.version_info >= (3, 7):